Almost daily right now I get asked to use WhoScored or Squawka to compare X player to Y player and I understand, because it’s entirely my fault having helped popularize stats in football with this blog and with my column on Arseblog News. And I have usually obliged the requests and will often post some boring old “here’s a box, with some numbers in it” style answer. It satisfies, or perhaps mollifies the crowds but really, let’s face it, people like shiny new things. So, I made you this:
What I did here was take Mertesacker and Koscielny’s numbers and mashed them up into one beast and then took Cahill and Terry’s numbers and mashed them up into an uglier beast. Then, instead of dividing by Per90 or by the number of matches that they played, I just used their bulk stats. So, clearances is the total number of clearances that each pairing made, interceptions is the same, tackles and everything except passes. I chose to do passes on a per game basis because it would really look weird to have several thousand events in one category and “two” in assists.
Now, as you can see, the four center backs are similar in some ways and different in others.
Similar: all four center backs clear the ball at nearly identical rates. Chelsea clear slightly more than Arsenal on a per game basis but because of injury to Cahill their bulk numbers are basically the same. Passes per game are also almost exactly the same and all four players pass the ball at an 87-92% rate.
Actually, Arsenal have the edge here because Mertesacker and Koscielny lead the League (no.1 and 2) in pass percent (not included in the graph above). Not only are the two Arsenal men overall better at making the average pass, they are vastly superior in long passes. This could be down to the fact that Terry and Cahill don’t have a target man up front but for whatever reason, Per-Koz have only misplaced 21 of their 161 long passes (13%) while Cah-Ter have misplaced 86 of 229 (38%). To make this point even clearer, Per-Koz have completed a total of 140 long passes and Cah-Ter 143, that’s despite the Chelsea players attempting 68 more long passes.
The other advantage for the Arsenal pair is in interceptions and tackles, which is shown above. The interceptions number (100-39) is almost entirely down to the speed of Koscielny. Koz could very well be the fastest center back in the League and it shows not only in his ability to steal the ball off opposition strikers (3 per game, 4th best in the League) but also in his ability to recover and get back for a block.
As for tackles, Mertesacker and Koscielny have attempted and won more tackles than Cazza-Tazza but the truth is that you don’t really want your center backs making a lot tackles because the dangers involved as last man. And Koz again gets the plaudits here, whereas Terry and Mertesacker are 52% tacklers and Cahill is slightly better with 57%, Koz is 63%. To put it another way, Terry and Cahill have only combined for 27 successful tackles, Koz alone has 32 (combined, Arsenal’s CBs have 56 successful tackles).
Where the Chelsea duo have the advantage is in aerial duels won. Both Chelsea CBs attempt more aerials and are more successful than the Arsenal pair. Cahill wins 73% of his duels (66/91) and Terry wins 66% (75/114). Meanwhile, Arsenal’s Big Flying German wins 73% of his duels (65/89), but Koscielny is only a coin flip at 52% and oddly has only even attempted 52 total aerial duels. Over his career, Koz has been better, 62% in his first year and 64% last season, so I have to wonder if his low numbers both in terms of attempts per game and in success isn’t by design on the part of Arsene Wenger and Steve Bould: especially on set play defense, where Olivier Giroud is often deployed to clear opposition corners.
The Chelsea duo also have the advantage in terms of the small numbers at the bottom: errors, goals, and assists. Because these are such small numbers (2 assists for Chelsea, e.g.) they could swing rapidly at any time over the next 10-12 games so, take them with a Himalayan grain of salt.
Not shown above is that when Mertesacker and Koscielny have started together this season (in the League) Arsenal have won 14. drawn 3, and lost 2. That’s good enough for 2.36 ppg. This is almost exactly the same as Gazza-Jazza who have played 17 together, won 12, drawn 1, and lost 1 for 2.35ppg.
That said, there is a significant population of people who will point out that for both of Arsenal’s losses with Per-Koz, Koscielny missed part of the game. Against Villa, Koscielny was shown a red card in the 66th minute, after which Tony Moon scored the 3rd Villa goal. Arguably, Arsenal were already in a losing position at that point in the game. Also, Kozzer came off injured in the 41st minute against City, after which City put four goals on us, though, again, the Citizens were already up 2-1 and again Arsenal were in a losing position. Still, if we take away the goals that Arsenal conceded when either Koz or Per were off the pitch, the Arsenal center back pairing have only allowed 12. Meanwhile, the Chelsea pair have allowed 13.
No matter how you look at it, this is an extremely close call. Do you prefer blockheaded lumberjacks pounding balls out of the backfield or nimble defenders stealing the ball and distributing to kick start a counter attack. It’s close, but I give this one to Arsenal’s center backs.
Because I’m biased.