Thursday, August 26, 2010

Chalkboards: Arsenal vs. Blackpool

Here's a few chalkboards from Arsenal's 6-0 beatdown of Blackpool.
Passing Chalkboard for Arsenal vs. Blackpool (click to enlarge)

Ironically, the passing differential was relatively low for the match. What is clear from the chalkboards is that much more of Arsenal's passing took place in front Blackpool's goal than Blackpool's passing in front of Arsenal's goal (see right hand side of each chalkboard).

Tomas Rosicky Passing Chalkboard (click to enlarge)

As the commentator's pointed out during the match, Tomas Rosicky carved up Blackpool. The chalkboard bears this out, showing many successful passes in the middle of Blackpools end of the pitch at a 90% success rate.

Team Shots Chalkboard (click to enlarge)

The team's play, especially Rosicky's, translated to far more shots for Arsenal than Blackpool. Arsenal's 30 shots were nearly ten times greater than Blackpool's four. Only 12 of Arsenal's shots were off-target, representing a 60% on target rate.

Ultimately, it was that increased number of shots that led to the six Arsenal goals.

MLS Playoff Predictions and Golden Boot Update: August 26, 2010

Continuing their upward climb

Another three weeks, another four points out of six for the Sounders. Another two teams at the top of the table turn green, while the percentages of the teams in the lower half of the final 8 continue to improve. It's time to take a look at where things stand two-thirds of the way through the season. As a reminder, here's how the color coding works.

Playoff Standings

MLS Predicted Finish as of August 22nd, 2010 (click to enlarge)

The Galaxy have continued their slow slide from their hot start. They're in a heated battle with Real Salt Lake for top seed in the West, and RSL now has the edge in projected goal differential and the points that should result from such a goal differential.

FC Dallas continues to impress, moving into the near certainty column with the Columbus Crew according to Sports Club Stats, while they are still yellow according to my projected goal differential and points methods.

New York's improvement by two spots has also resulted in a 27.4 point increase in their playoff chances, making them a virtual lock according to Sports Club Stats. Meanwhile, San Jose is on the verge of locking up their participation in the MLS playoffs and Colorado's chances dropped slightly as they moved down to the 7th position.

Things are very interesting in the 8th and final playoff spot. The Seattle Sounders have continued their unbeaten streak, while the Chicago Fire are unbeaten in their last four league matches. The teams are projected to finish within one point of each other, while the goal differential gap can be explained away by the Sounders 0-4 drubbing by LA. The teams play each other twice over the next month, and both face pretty brutal schedules throughout the last third of the season. The Sounders face Real Salt Lake, Columbus, Toronto, and Houston, while Chicago face LA, Toronto, Real Salt Lake, San Jose, Dallas, and Houston. What this really comes down to is which team - Seattle or Chicago - wins their two game series over the month. If they split the points, it's a toss up. A tie and a win for either is good, and two wins for either puts them in the driver seat for the eighth playoff spot. Throw in the fact that Seattle's original DP, Freddie Ljungberg, now plays for Chicago and you have some real drama.

Golden Boot Update

Golden Boot Standings for August 22, 2010 (click to enlarge)

All of the goal scorers are continuing to cool as the season goes on. Edson Buddle has now slipped to the top 10% of historical MLS goal scorers in terms of games per goal, while he was in the top 5% three weeks ago. Juan Pablo Angel is the only other player over the 50th percentile, while Alvaro Sobario's hot streak has ended and he has slipped to scoring a goal less frequently than every other match.

Sunday, August 22, 2010

New Social Media Buttons

So I have been on Twitter for a number of months now, and I am finally getting around to adding the standard Blogger social media buttons at the bottom of each post. Please feel free to use those buttons for any of the services with which you have an account. I appreciate all the help in spreading the word about my blog.

Tuesday, August 17, 2010

Statistics as Conversation Starters

I got the following email in response to an earlier post from a friend who has been an Arsenal supporter much longer than me.

Up until last year, [my wife] and I have been huge fans of Sagna and Clichy, but last season we got really frustrated with both of them. Defensively they are great, but too often they make the pass (cross) that makes us lose the ball. Especially Sagna C-A-N-N-O-T cross the ball. Always too low, or to an opponents feet, and then we are caught in a counter attack. Against Liverpool Sagna made 6 attempts to cross the ball into the box- all unsuccessful! Which must be considered a crime now when we have Chamakh who is a beast in front of the goal and famous for his headers. Check out the attached chalkboard.

It's interesting to see that only Clichy had a worse completion percentage than Sagna. Perhaps my theory of missing RvP and Fabregas is only part of the story. If my friend is correct, it won't matter who Arsenal stick in the middle up front if they can't get them the ball due to poor passing.

You Don't Need Data to Prove Some Things

Good statisticians never use statistics to prove something we already know to be true. Using them to prove something that is intuitive is a massive waste of resources and time, no matter how entertaining the subject. This study (HT: John) clearly falls into this category. While not related to football, it earns my "BS Stat of the Day" award in the "You're Kidding!?!?!" category.

PS - I hope guys understand the natural end game of such decision making. C'mon, haven't you guys watched enough horror/reality movies to know where this all leads?

Sunday, August 15, 2010

New Season, Same Old Arsenal

When the 2010-2011 Premier League schedule came out, I circled the season kickoff between Arsenal and Liverpool. You see, if there's one set of matches I will always make time for at the George and Dragon (rather than my own couch) it's the two Premier League ties between the Gunners and the Reds. It's a way for me to enjoy the beautiful game with one of the guys who got me into the sport, and he just happens to be a Liverpool fan.

I say "make time for" because most Premier League matches are on the weekends - when I have my children from my first marriage three out of every four a month. It's not right for me to take time away from them, and you can imagine it is very difficult to find a babysitter for that time of day. So, on these two weekends a year, I call on my now-wife (then-fiance) to watch the children while I enjoy some Premier League action early on a weekend morning.

A lot has changed since I last watched my Gunners at the George for last year's second win against Liverpool. I've made it through my first World Cup as a dedicated fan. I also got married this summer. Too bad my team hasn't changed much during that time.

As I showed up at the George this morning I was greeted by a starting lineup with no van Persie, an active squad without Fabregas, and the painful reminder of no goal keeper upgrade by seeing Almunia's name over the goal. It didn't take long to make this reminder of 2009-2010 turn into a painful reality.

Almunia gave up another early second half goal that any other goal keeper would have turned into a picture perfect save. Why Arsene Wenger refused to make a keeper his top transfer priority this offseason is beyond me. Arsenal has plenty of defensive holes to worry about, but the squad has absolutely ZERO confidence in the goal keeping squad. Watching that early defensive collapse and Almunia failure had me muttering, "not this again."

On the offensive side, it was yet another match with no van Persie and no Fabregas in the starting lineup. This translated to a lot more passing than usual, even for Arsenal! Passing statistics for both teams were:

  • Arsenal: 451 successful passes out of 511 attempts
  • Liverpool: 193 successful passes out of 263 attempts
This translated to a total pass differential of 248 in favor of Arsenal, a total pass ratio of 1.94, and a successful pass percentage difference of 14.9%. Comparing these to the distribution of the same statistics from Arsenal's 2009-2010 campaign, one finds that these rank in the 65th, 63rd, and 85th percentile, respectively. This means that Arsenal passed a little bit more frequently than last year's average, but had a far better pass accuracy than the opposition compared to their performances last year.

A graphical representation of all that passing can be seen in Figure 1.

Figure 1: Passing Chalkboards for Arsenal vs Liverpool (Aug 15, 2010)

The benefit of all this passing showed up in the number of opportunities for Arsenal, but not perhaps the quality of them. They had double the shots (18 vs 9), with Liverpool benefitting from a higher proportion of blocks (6 for 33% vs. Arsenal's 2 for 22% of the shots). Watching the match, I am sure many of those Arsenal shots came in that flurry of action 10 minutes from the end.

The frustrating reality for an Arsenal fan like myself is that without van Persie or Fabregas on the pitch, teams are not fearful of all the passing. Arsenal has no real finisher under those conditions, and they truly look like a team just happy to keep passing for passing's sake. In reality, they have a bunch of role players on the pitch that are used to passing to set up someone else. Arsenal is in real trouble if they have to go through yet another season with such a situation being the weekly reality. I hope that is not the case.

Sunday, August 8, 2010

Arsenal '09-'10: Passing

With the start of the 2010-2011 English Premier League season less than a week away, I will embark on a series of posts analyzing Arsenal's 2009-2010 campaign and see if anything can be learned from it. The Gunners finished a distant third to Manchester United and Chelsea in 2010.

All data used in this series comes from the Guardian's Premier League Chalkboards. As I was made aware of these chalkboards via a fellow Gooner in an email lamenting the high number of passes in a particular match from last season, I will dedicate my first post in this series to looking at Arsenal's passing. I will look at three statistics - number of passes, ratio of Arsenal passes to opponents' passes, and percentage of successful passes - and compare Arsenal's performance in each against their competition.

Total Number of Passes

One of the common comments (criticisms?) of Arsenal is that they pass so much more than their opponents. This can manifest itself in supporters' frustrations as it sometimes seems that the Gunners seem to enjoy passing for passing's sake and less about setting up a score. It can also be a sense of enjoyment, as such an emphasis on passing can sometimes open up opportunities not realized by other teams' strategies. The first task I set about was quantifying just how many more times Arsenal pass in a match vs. their opponents.

Looking at my transcription of the Guardian data, I took the differential in the total number of passes made by Arsenal and their opponent for each of the 38 matches in last year's Premier League season. This is noted by the variable PD. I then used Minitab's "Graphical Summary" module to look at the data's distribution. See Figure 1 for that module's output.

Figure 1: Graphical Summary of PD for Arsenal's 2009-2010 Premier League campaign

One can see that nearly all of Arsenal's matches end with them making a greater number of total passes than the opposition (note: a review of the raw data shows only two matches where this is not the case). The graphical summary also aids us in quantifying the statistical likelihood of the value of the average number of passes in excess of their competitor made by Arsenal. We can now use the one-sample t-test to quantify the range of that average as the p-value of the normality test is greater than 0.05.

Figure 2: One sample t-test of PD for Arsenal's 2009-2010 Premier League campaign

The one sample t-test shows us that Arsenal do indeed have a statistically significant mean difference in their number of passes. To be exact, the mean is 180.5 passes per match, with the 95% likelihood of the true average being 153.4 passes or greater.

One other question that could be asked is: Do Arsenal show a statistically significant gap in their increased number of passes against the competition at home vs. while on the road? Turning to my copy of the Guardian data, one can see that the data has been categorized as "home" vs. "away". Luckily, both sets of data, when grouped by venue, also test to be normal. This means a two-sample t-test can be applied to the data to determine if there is a statistically significant gap between home vs. away passing differential. See Figure 3 for the results.

Figure 3: Two sample t-test of PD for Arsenal's 2009-2010 Premier League campaign

To declare a statistically significant difference, we'd need to see a p-value of 0.05 or less. In this case, the p-value for the test statistic is 0.054, which is just outside the acceptance range. While we can't statistically declare there is a difference, it looks pretty much like there is one with Arsenal making 52 more passes vs. the opposition when at home as compared to on the road.

Ratio of Arsenal Passes to Opponent Passes

One other way to look at the passing gap is to look at the ratio of the number of Arsenal passes to those of the opposition (PR). When looking at this statistic, we get an even cleaner distribution. See Figure 4 for the graphical summary.

Figure 4: Graphical Summary of PR for Arsenal's 2009-2010 Premier League campaign

As the results indicated a normal distribution (p-value > 0.05), a one-sample t-test is used again to quantify the size of the ratio. See Figure 5 below.

Figure 5: One sample t-test of PR for Arsenal's 2009-2010 Premier League campaign

The result in Figure 5 shows that, on average, Arsenal makes 72% more passes than the opposition. It also shows the 95% likelihood of the true average being 59% or greater.

What does this look like within a match? One way to look at it is via the Guardian Chalkboards. Figure 6 shows the chalkboard for the passes made during the Arsenal/Sunderland match on February 20th, 2010.

Figure 6: Guardian Chalkboard for Arsenal/Sunderland Match (Feb 20, 2010)

This match represented the peak value for the ratio of Arsenal-to-opponent passes, a value of 2.67. The only two times Arsenal fell below 1.0 for this ratio was the August 29th, 2009 match at Manchester United and the September 26th, 2009 match at Fulham. Unfortunately, a two-sample t-test of the pass ratio data for home vs. away matches did not yield a statistically significant difference, therefore we cannot draw a conclusion of home vs. away passing ratio differences.

Passing Accuracy

A final way to look at Arsenal's passing is to look at their accuracy of passing vs. the competition. The statistic is the difference in passing accuracy (number of successful passes/total number of passes), and is expressed via the term P%D.

A graphical summary of P%D is found in Figure 7.

Figure 7:
Graphical Summary of P%D for Arsenal's 2009-2010 Premier League campaign

Figures 8 and 9 show the results of the one- and two-sample t-test that were performed on the normally distributed data set for P%D.

Figure 8:
One sample t-test of P%D for Arsenal's 2009-2010 Premier League campaign

Figure 9: Two sample t-test of P%D for Arsenal's 2009-2010 Premier League campaign

One can see that while Arsenal is 7.82% more accurate than their competition when it comes to passes, there is not a statistically significant difference in their passing accuracy at home vs. on the road.


During the 2009-2010 Premier League campaign, on average Arsenal:
  • made 181 more passes per match than their opposition
  • made 72% more passes per match than their opposition
  • passing accuracy was 7.2% higher than their opposition
What did this translate to in terms of goals and wins? That's for a subsequent post!

Monday, August 2, 2010

MLS Standings Update: August 2, 2010

The only Fredy the Sounders need: MLS July Player of the Month

It's been a fun several weeks off. I am now married, and the new wife and I have enjoyed a relaxing several weeks of doing anything we wanted. That included catching the Seattle Sounders 2-1 victory over the Colorado Rapids. A lot has changed since my last MLS-related post nearly a month ago. Let's get to it!

Projected MLS Finish as of August 2, 2010 (click to enlarge)

LA fading and Seattle coming on strong

The inevitable is beginning to happen - the LA Galaxy are regressing to historical means for the team in the top league position. In the period of one month they have given up a projected nine points, and are now projected to finish just slightly behind the 64 points claimed by the Houston Dynamo in 2005. Their porous defense has cut into their projected goal differential, lowering it from 40 to 28 over the last month. Adding to their misery, the Galaxy have also been bounced from the US Open Cup and CONCACAF Champions League in the past month. LA is still assured a spot in the MLS Cup playoffs, but their top seed is in great doubt as they falter and Real Salt Lake continues to perform well.

At the northern edge of the West Coast, the Seattle Sounders are rallying. While still a long shot for the playoffs, they've improved their chances by 25% with a draw against Dallas and wins against DC United, Colorado, and San Jose. The Sounders have big matches against the Dynamo, Chivas, and Fire (the return of Freddie Ljungberg), who they are fighting for the final playoff spot. The Sounders suffer from the fact that they are tied with LA with the most matches played to date (19), providing their competition with 2 to 4 games in hand. Nonetheless, this is an impressive turnaround for the team, with the catalyst being the benching and trade of Ljungberg and the additions of N'kufo and Fernandez. We'll see if they can keep league form as they also balance the US Open Cup semifinals in early September and the initial group play matches of CONCACAF Champions League.

Major Movers

Biggest gainers: Sounders FC (+3), San Jose Earthquakes (+2), and Chivas USA (+2). With all the movement coming in the Western Conference, it proves the season long competitiveness of it and how tight the race for the final playoff spot will be.

Biggest losers: Colorado Rapids (-2), Houston Dynamo (-2), and two teams at -1

Golden Boot Update

The table below summarizes where the top 5 goal scorers stand versus historical data. One can see that Edson Buddle is still on his record pace from a games player per goal perspective. Sounders castoff and Philly start Sebastien Le Toux has crept into the standings with his excellent form of late, and is only behind Juan Pablo Angel and Buddle in terms of goal scoring efficiency.

MLS Golden Boot Standings vs. All MLS Goal Scorers in League History (click to enlarge)