Simple question: Have Arsenal progressed this year? Are they better than they were last year? To answer these questions I am going to post 4 graphs which that will get us part, if not all, the way there.

So, we compare certain metrics from the 12/13 season to the 13/14 season, using league data only (incentives).

TSR/Shots Share%/Corsi/Whatever

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These charts show Arsenal’s rolling share of the shots taken throughout their fixture lists. Arsenal were recording a higher percentage share of the shots in 12/13 than they currently are in 13/14. This is not a good thing.

Some folk may point to shot quality/locations but there’s usually a reason that teams take less shots and/or concede more shots and, usually, those reasons aren’t positive.

Shots On Target Ratio

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A bit noisier, but a few things stand out: This time last year once the horrendous injury list had eased Arsenal went on a season saving run of form to finish 4th ahead of the Tottenham. A part of that form was due to an improvement down the strecth in Arsenal’s SoTR which picks up from game 23 or so and finished a fraction shy of 60%.

This season (13/14) Arsenal’s SoTR was pretty good, if not elite, for the first 22 or so games before nosediving. Injury lists play their part, as do quality of opposition issues. Still, it appears that Arsenal won’t be able to equal last years ~59% SoTR number. Arsenal’s 13/14 number is currently at 55.3%.

Goal%

Goal% = Goals for/Total Goals(goals for+goals against)

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Goal% is driven by a teams shots and target ratio and its PDO number. Arsenal’s 12/13 number consistently improved from around the 10 or 11 game mark – driven by SoTR (above) and an improving PDO.

Arsenal’s 13/14 Goal% was driven by good, not great, SoTR and a super high PDO that was at 110 or higher for 21 of the 31 weeks of the season so far. League average PDO is 100. Teams who spend a high amount of minutes in leading positions will post PDO’s north of 100.

We can see that Arsenal’s 13/14 Goal% has cooled off and this is due to SoTR cooling off by a few percentage points and a gradual cooling of PDO.

Points%

Arsenal’s shots and shots on target numbers may not have convinced everyone that there is real year on year decline and that’s ok. Maybe goal% didn’t convince anyone either! How about we look at points% then?

Points% = points/total points available

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This graph is super cool in a scary kinda way. We can see that Arsenal showed amazing improvement in the second half of 12/13 (SoTR, PDO improved). Arsenal’s 13/14 season looks like it is going the other way. Decline, decay, injury-hit squad unable to cope with a tough sked, tactics or whatever. It is a frightening graph.

Whichever we slice the information it doesn’t look good:

  • Arsenal have a significantly lower TSR year on year.
  • After a good start to the season in SoTR (easy sked?) Arsenal’s number has cooled in recent weeks and is now worse than 12/13’s SoTR number.
  • Goal%, driven by a high PDO and some good SoTR numbers has cooled and now sits below 12/13’s number after the exact same number of games.
  • 13/14 Points% remains the only stat that is currently better than 12/13, but with a poor TSR, declining SoTR and PDO numbers Arsenal’s 13/14 Goal% may come dangerously close to touching 12/13’s number.

In short: Context is important, inuries to key talent, lack of striker and wing options may have handicapped Arsenal’s ability to post better underlying numbers. The question is by how much have those issues handicapped Arsenal? We don’t know.

Arsenal may well surpass last seasons points total but they may well do so having posted poorer shots and shots on target numbers. People may point to shots quality (and some score effects) and say “who cares if they are shooting less but shooting better” and you know what, maybe they’re right, but for me I would rather a team posts high percentages of the shots and shots on target share whilst still trying to take the very best quality of shot that they can.

 

  • toshack

    Interesting Ben,
    Let’s see if Arsenal can dig out a last burst to defy the stats trends (or not).
    Tonight’s game will be important for sure.

  • gjames

    Pretty simple imo – regardless of how Arsenal got a PDO advantage over their rivals (and are we talking City and Chelsea here or Tottenham and Everton?) it can’t be maintained in the v. long run. The long run trends in shot numbers are bad.

    Going to be a good article to refer to regardless of how Wenger’s contract wrangles are resolved.

  • Errorr

    Great Stuff!!!

    One of the areas that other sports are advancing at are health indicators. Firstly, I wonder if Arsenal’s injury problems are cultural. What I mean is whether the high injury rate is due to usage (game time), training, or training staff issues; or is it that Arsenal has too often ignored injury history in acquiring players.

    Based on my reading of other sports Football is far far far behind in this area of sports science. I know there are some teams (including Arsenal) that at least track minutes played but I don’t know how far beyond that they go. These health factors matter more and more and even in the US sports open to data analytics they are just scratching the surface.

    Of the things we have learned from other sports are that injury is firstly a skill. It is partially genetic but it is just as much about skill on the pitch. In the NFL teams are starting to learn how to re-train wide receivers to better protect them from hamstring injuries which is something you can teach. (in WR at least starting from a dead stop and sprinting red-lines the hamstring, taking a slow stutter step early allows players to ramp up hamstring stress). Some players are just injury prone (although you have to seperate out the injuries that identify the injury prone from injuries that have large amounts of random chance).

    Secondly, modern physio science has made huge leaps and bounds in the past few years. Early the last decade the Phoenix Suns medical staff became famous for being able to manage older and injury prone players. Putting money and effort into this area could have a massive impact on team quality over a season.

    What I would like to see eventually is data on injury rates that is finer than the rough minutes/games played. Ideally we would search for correlations to injury rate based on distance traveled, minutes, time spent above certain speed intervals, tackles/lunges, training time, pitch location/role, and even # of headers.

    • Errorr

      A slight digression on the last note:

      As an American I am appalled by the treatment of concussions in the sport. I regularly see concussions go unremarked. It was nice to see a brief uptick in awareness after the Lloris/Lukaku incident but that has seemed to fade. I hope it doesn’t take a lawsuit to cause change but that is where things are headed (no pun intended).

      I will be surprised if headers are not officially banned in youth soccer in the states within the next decade.

      • David

        There was a movement for that about 20 years ago in the states until real, actual…umm…science was performed and showed regular heading of a soccer ball – even at the age of 6-8 – has very little [if any] long-term effects. If nothing more has been made of it in 20 years I have a hard time believing there’s any validity behind that statement.

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