Arsenal’s numbers say they’re Man City’s main competition

It has been years since Arsenal contended for the English Premier League title. This year could be different. Unlike other seasons when the Gunners took early leads only to see them disappear as the second half rolled on, it is not clear which other sides can overtake them. Certainly Manchester City have the quality, but Manchester United are still licking their wounds after a 3-0 thrashing from the Gunners, and Chelsea remain stuck in 15^th place, as well as possibly an alternate universe where none of their players are any good anymore. With just one serious contender to beat, the door is open.

On top of that, Arsenal have been playing truly excellent soccer. The top line numbers of 22 points from 10 matches and a plus-10 goal difference are good, but the underlying numbers are better still. Arsenal have scored on only 16 of their 200 shots (their other two goals have been own goals), a conversion rate of eight percent, where usually Arsene Wenger’s sides produce conversion rates in the 10 to 12 percent range.

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Indeed, by expected goals, a statistical measure of the quality of chances produced and conceded, Arsenal have created chances which would typically lead to about 24 goals, and over time it is typically the case that teams start finishing their chances at the expected rates. The Gunners are top of the table, and they could easily get better as they improve their chance conversion.

The following graphic displays Arsenal’s chances created and conceded this season, with larger squares representing higher “expected goals” values. Pinks boxes are goals.

This expected goals difference of plus-15 is best in the league, with only Manchester City running close at about plus-14. This means that Arsenal have been on average 1-2 goals better per match than their opponents. This is an extreme number. In the top European leagues, only Real Madrid, Barcelona, Bayern Munich and Borussia Dortmund have superior expected goals difference per match.

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Over the last five seasons, there have been 28 clubs in the big four European leagues which started the season with an expected goals difference better than plus-10 over their first ten matches. Of these 28, exactly half (14) won their leagues. Another 10 only failed to win the league because another club who also had an early xGD of better than plus-10 finished above them. It’s a good list to be on.

There are a couple cautionary tales here. Chelsea and Arsenal kicked off the season hot in 2010-2011 and were in first and second on Halloween, but were overtaken by a Manchester United side that had started the season a more disappointing 5-5-0. Arsenal slipped all the way to fourth. Last season, Napoli never realized the promise of their great early statistical record and struggled to a fifth-place finish in Serie A.

It is certainly possible that this Arsenal side could fall apart as well. But those are just two clubs among a long list of successes. With strong early results and a superior statistical record, overall the Gunners have an enviable set of historical comparands.

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So, how are they doing it? And will the injuries to Theo Walcott and Alex Oxlade-Chamberlain derail a promising season? To the second point, it does not appear that Walcott has been the difference-maker. Arsenal have converted more of their chances with Walcott on the pitch, but the underlying chance creation statistics are very similar between Walcott and Giroud. The players to watch, rather, are Alexis Sánchez, Mesut Özil and Francis Coquelin.

In attack, otherworldly play by Sánchez has been Arsenal’s primary strength. Not only has the Chilean forward scored six goals in 777 minutes, but his underlying statistics suggest he could do even better. Based on his shot attempts and assists, Sánchez has about eight expected goals and two expected assists. These numbers have no equal in the EPL this year.

This graphic also makes clear the primary axis of the Arsenal attack. Sánchez leads the league by a wide margin in expected goals, meaning that he is doing better than anyone else at getting himself free in dangerous spaces where he can threaten the opposition goal. And Mesut Özil with about six expected assists is likewise the class of the league in assisting shots in dangerous locations. The Arsenal attack should continue to run just fine with Olivier Giroud up top — note also his strong shot contribution — as long as Özil and Sánchez are clicking.

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On the defensive side, it is Francis Coquelin who makes Wenger’s tactics work. The French defensive midfielder is a reactive player, at his best seeing danger and moving quickly and precisely to stamp it out. This leads to some peculiarities in Arsenal’s statistics. Most of the best sides in the English Premier League concede about 10-15 completed passes per match into the “defensive midfield” zone, the area about 30 yards wide and 20 yards deep extending back from the top of the eighteen-yard-box. Arsenal have allowed about 18 passes per match into this area. It is notable that Coquelin’s job does not seem to be to prevent such passes being played.

Rather, once opposition teams get into the defensive midfield zone, they can’t get out. Either they are pushed backward or they lose possession. This map of Coquelin’s tackles shows how often he breaks up play in this zone.

Obviously tackles make up a small percentage of defensive stops. Most of the time it means forcing a bad pass or pushing the opposition team backward out of the attacking zone. But Coquelin’s action map shows where he is most effective. Arsenal’s opponents may get into that defensive midfield zone about 18 times per match, but they only manage to complete a progressive pass out of this are three or four times per match, which is the lowest total allowed in the EPL. So Arsenal’s defense concedes possession in a relatively dangerous area but counts on Coquelin, assisted by the center backs and fellow midfielder Santi Cazorla, to prevent any progression from there.

These tactics, with a dynamic attack driven by Sánchez and Özil, backed up by a bend-but-don’t-break defensive midfield, have propelled Arsenal to the top of the table. The underlying statistics suggest this has not been a patch of luck but rather a deserved run driven by excellent chance creation. While Manchester City may still be favorites, the Gunners are right in the thick of the Premier League title race.