How Do You Solve a Problem Like Mesut?

One of the big surprises in my analysis of Arsenal’s Starting XI was the number of players the Random Forest model preferred to Mesut Ozil. As a reminder, the Random Forest thinks about 40% of midfielders in the big 5 European Leagues would help Arsenal if they replaced Mesut Ozil.1 Here’s the graph:

Replacements Arsenal

I’ll admit to being surprised as well, so I did some first-cut exploratory analyses to see what exactly is going on with my data and I wanted to present them here. The first was looking at the distribution – seeing how much of an improvement we’re talking about, and how many players there are. Here’s the density plot of the overall distribution and Ozil’s place on it:

Ozil Replacements

It’s fairly normally distributed2, with a fairly narrow distribution (most players falling between +/-2 points of Ozil). It peaks at +5 points, and bottoms out at -7 points, but most players don’ t offer a significant increase over what Arsenal could expect with Ozil. I plotted out the distribution by points to more clearly see what proportion of players would help Arsenal gain different amounts of points.3

Ozil Proportion Increase

You can see the significant dropoff as we get higher in points – a lot of players gain Arsenal *some* points over Ozil, but we’re down to around 10% of midfielders are a 2+ point increase, and virtually no one4 players get Arsenal 3 or more points. This goes back to Wenger’s idea that it’s hard to find players who would improve a team like Arsenal.

So who are the players who can improve over Ozil? Here’s the top 10 (all are a 3+ point increase):

Player (Team)
Jedinak (Crystal Palace)
Medel (Inter Milan)
Verratti (PSG)
Keita (Roma)
Crisetig (Cagliari)
Magnanelli (Sassuolo)
Hlousek (Stuttgart)
de Rossi (Roma)
Toulalan (Monaco)
Tiote (Newcastle)
Osman (Everton)

The most interesting part here is that virtually none of these players, if any, would fit in a #10 role. Most of them are defensive midfielders, offering tackling and defensive support. A deeper look at the list shows a decent number of players who would be comfortable in an attacking role (several of Chelsea’s attacking mids are on that list unsurprisingly), but the real gap here seems to be Ozil’s defense. That’s not his role, but it shows a gap in Arsenal’s style that could be useful for them – someone like Yaya Toure who can play in a box-to-box role instead of a pure central attacking midfielder might be a good fit (and is a 2.5 point increase according to my Random Forest model, even with last year’s relatively down year for him), or Roma’s Daniele de Rossi who is almost a 4 point increase.5. If I were advising Wenger, I’d recommend a look at Lorenzo Crisetig  at Inter Milan – he’d be relatively inexpensive, can play anywhere in the center of the pitch, and at 21 has a huge upside.

There’s probably more to be gleaned from this, but it’s interesting to see why exactly the model doesn’t like Ozil as much as some other options, who I have a ton of respect for as a player. It’s also interesting to see how this can highlight deficiencies in the team and potential tactical adjustments that could be made to improve teams without overhauling the entire lineup or style.

  1. No one seemed surprised Aaron Ramsey’s number was almost as high…I almost feel bad for him.
  2. Or close to a bell curve
  3. This was a horrible sentence. My apologies to anyone who ever said I was a good writer at some point in life
  4. The exact number is 36/1058 players in the midfielders database
  5. His age would probably have made him a bad choice, although with the potential gain he might have been worth it if Arsenal’s going to take advantage of this big opportunity to win the EPL

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