The end of the 2016/17 season was the worst under Arsene Wenger’s tenure at Arsenal. As uncertainty mounted over whether Arsene would sign a new deal the Gunners suffered a series of humiliating defeats to small clubs like Watford, West Brom, Palace, and Tottenham. Arsenal finished 5th for the first time in Wenger’s career, outside of the Champions League places, fan unrest mounted a bi-plane and flew banners over the stadium, and yet the club retained his services. Little did we all know that things could get worse, much worse.

Arsenal’s tenure under Wenger was marked by an odd consistency, rarely challenging for the title in his final ten years, and yet also rarely looking like they would drop out of the top four. But the end of that 2016/17 season should have been a warning to the club. A warning that things were going to take a much more sour turn for the Alsacian.

The web site understat.com has Arsenal’s expected goals data all the way back to 2014/15. I might quibble with some of the values that they assign to shots sometimes but their data tends to match up with my own personal formula and since it is publicly available (and my database isn’t) I like to use their data whenever possible. That way you all can check my work.

I looked at every one of their expected goals numbers for every Premier League match Arsenal played in back to August 2014. That’s 202 Premier League matches for Arsenal.

I then took a simple five-game moving average of the expected goals difference in each match and produced this graph:

Wenger’s Arsenal peaked in matchday 13 of the 2015/16 season. At that point they had an expected goals difference average of 2.04, per game. Yes, per game, folks.

Cazorla’s injury devastated both the player and the team. With Cazorla out and no one able to make up the slack, Arsenal hit rock bottom on matchday 29, when their expected goals difference over the previous five matches was just 0.10.

There was a slight uptick toward the end of the season and continuing on into the next season but once again Arsenal hit a post Christmas snag. This time, however, the results were much much more problematic and Arsenal hit a Wenger career low -1 expected goals difference per game average.

At that point, the club should have acted. Wenger was out of contract that summer and it was clear that the club couldn’t move forward with him at the helm. And I say that without the slightest disrespect to the things he had done for Arsenal. It’s just that everyone’s time comes to an end.

Arsenal finished the season with a very strong expected goals difference thanks to some massive wins over Burnley, West Ham, and Southampton – which is why you see such a big spike right after – but missed out on 4th place because of a loss to Newcastle.

Perhaps that end-of-season push explains why he got another deal? Either way, it was a false dawn and eventually the reality would catch up.

Another way to look at this expected goals data is to just tally up the number of games in which Arsenal had more expected goals for than they had expected goals against.

In 2014/15 Arsenal had a superior expected goals in 30/38 matches. In 2015/16 that number went up to 33/38 matches and I bet you can even name the five bad matches from that season (Chelsea x2, Southampton, Tottenham, and believe it or not, Swansea).

But the next season, Arsenal struggled to find even expected goals superiority and the number of games where Arsenal had a superior xGD was just 23/38.

Season Matches with +1 or more xGD Matches with -1 or more xGD % of Matches with Positive xGD 2014/15 17 2 79% 2015/16 18 3 87% 2016/17 14 5 61%

I also marked the number of times that Arsenal had a +1 or greater xGD and the number of times we had a -1 or greater (lesser) xGD. For example, matchday 25 of 2016/17, Arsenal played Hull and had an expected goals of 3.12 and an expected goals against of 0.47. That counts as one of the +1 or more. And on matchday 33 against Tottenham, Arsenal had an expected goals of 0.59 and an expected goals against of 3.46 so that goes in the -1 column. Got it?

As you can see from the numbers above, once again, the 2016/17 season is one which Wenger was clearly slipping, though, you could make an argument that the results weren’t so terrible. After all, Arsenal were only dominated five times in the League that season.

Wenger’s final season is widely considered to be Wenger’s worst and from a defensive perspective it was: 49 expected goals conceded, 51 actual goals conceded. And as we see from the 5 match moving average line, Arsenal were in a real mess with Wenger.

Here’s the expected goals for and against averages from the same period, the red line represents the defense:

This graph shows that the defense at Arsenal has grown progressively worse over time, and also that the last two years, the offense has dried up. That data is also reflected in the xGD chart at the top of this post. There I have marked when the Emery era began and the chart shows, along with the graphic directly above, that Emery’s version of Arsenal are not only not hitting the offensive highs that Wenger achieved, they are also not defensively solid.

And the end of the 2018/19 season should have been all the data that the club needed in order to see that Emery wasn’t right for the job. Under Emery, Arsenal’s five match expected goals difference average dropped to a 188 match low of -1.10. Emery was able to bring that back a bit with a big win over Burnley on the last day of the season but still ended the season on a negative expected goals difference per game average.

But what I think is truly aggravating for Arsenal supporters is the sheer number of matches that Arsenal have been bossed by the opposition. If I use that same metric above with the number of games that Arsenal have a +1 or more xGD and a -1 or more xGD, Emery’s Arsenal had a lot of games in which his team were simply hanging on for dear life: 10 of them last season and already 2 of them this season.

Season Matches with +1 or more xGD Matches with -1 or more xGD % of Matches with Positive xGD 2014/15 17 2 79% 2015/16 18 3 87% 2016/17 14 5 61% 2017/18 17 4 63% 2018/19 12 10 61% 2019/20 0 2 42%

And the worst bit is that he’s not improving the offense. So far this season, Arsenal have zero matches with a +1 xGD and only 42% (5/12) matches even have a positive xGD at all!

In fact, since matchday 24 (15 matches last season plus 12 matches this season) of last season Emery has only had 13 positive matches and 14 negative matches. In that time he’s also only had 6 matches with a +1 or more and six matches with a -1 or more. That includes Arsenal’s largest ever negative expected goal difference in a match when Emery’s Arsenal conceded 3.68 expected goals and only created 0.60 expected goals to Rodgers’ Leicester in matchday 36.

That run of terrible form coincides with Bellerin’s injury. But even if we return to Emery’s “glory days” of the first 22 League matches of his Arsenal career, he only had a positive expected goal difference in 64% of those games and he had 5 games which Arsenal had a +1 or more expected goals difference but 6 matches in which we had a -1 or more expected goals difference.

For me there’s no question at this point. The best we can expect is that Unai Emery will go back to being as bad as Wenger was at his worst. And at worst things will get much much worse.

The board was faced with a similar choice in 2016/17 and not only failed to act but took the wrong decision. Let’s hope they have learned their lesson.

Qq

Source: understat.com