On Saturday St. Johnstone beat Aberdeen 2-0 despite being outshot 13-8 and the xG being in favor of Aberdeen 1.10-0.66. It was a pretty typical match for St. Johnstone this season as they have a negative xG differential and TSR and TSoR’s below 0.5 meaning they allow
more shots and shots on target than they take. Despite this, Tommy Wright has the Saints in the top 6 again, which they have been every year he has been in charge and seemingly destined for Europe with a 4th place. Wright has a 44% winning percentage, only Owen Coyle has a higher percentage at St. Johnstone in much less games than Wright (Coyle was the last manager Transfermarkt had win numbers for). So what exactly is Wright been able to do to have his club finish with less shots than their opponents and a lower expected goals but still be destined for Europa League qualifiers?
Many have credited St. Johnstone’s success to their ability to convert the chances they do get. Goal conversion rate has been a hot topic in football analytics lately. Is finishing ability a skill that differs between players? Will it usually regress to the mean? The godfather of Scottish football analytics, Seth Dobson, did a great, easy to understand article discussing conversion rate in Scotland. In his article, Seth found that it takes usually around 3,000 shots before conversion rate stabilizes in the SPFL. Before that, conversion rate has huge variation, swinging up and down. Seth also found that Celtic has a higher conversion rate than the rest of the league, while the rest of the league has an average conversion rate between 13-15%.
With that 13-15% average range in mind, let us look at St. Johnstone’s conversion rate since Tommy Wright has been at the club. As we see in the graph below, St. Johnstone had a goal conversion rate of 13.26% in 2013/2014, 11.85% in 2014/2015, 16.57% in 2015/2016, and 13.86% in 2016/2017. This works out to an average 13.97%. We see their conversion rate slip below average in 13/14 but then it rise above average in 15/16. So it does not seem that St. Johnstone are any better or worse than the average SPFL club at finishing chances in Tommy Wright’s time at the club.
Furthermore, their expected goal numbers this year are not anything to write home about. As I previously mentioned, they have a negative xG difference so far this year. They are 7th in xG per game and 9th in xG per shot. It does not seem that the success Tommy Wright has had is due to St. Johnstone’s attack.
If it is not St. Johnstone’s attack that is leading them to success, than surely it has got to be their defense that is leading them to success. Well, only Dundee and Motherwell have conceded more shots than St. Johnstone have this year. Yet, St. Johnstone have the lowest Conceded Conversion Rate in the SPFL this year at 9.83%. We know not every shot is equal and we can measure shot quality with expected goals. Though when we look at their xG conceded numbers we see they are 7th in the league xG against, which isn’t awful but isn’t great either. However, when we look at St. Johnstone’s xG Against per shot, we see only Partick Thistle, Celtic, and Rangers have a lower xG per shot allowed. St. Johnstone are allowing a lot of shots, but many are low quality chances.
Exploring the type of chances the Saints defense allows further, we can look at the number of danger zone shots they allow. The average number of shots allowed in the danger zone (the area in the 18 yard box in between the 6 yard box) in the SPFL this year is 45.62%. However, only 41.63% of the shots that St. Johnstone have allowed have come from the danger zone. Another sign that while St. Johnstone allows a high number of shots, they are lower quality shots than the rest of the league typically allows.
So we see St. Johnstone have been particularly good at limiting opponents to worse shots than much of the rest of the league. In addition to providing me with data that hasn’t been available for Scottish football publicly, the good folks at Strata have also attempted to quantify the defensive pressure a shot faces when taken. Using a scale of 0-5, they base the defensive pressure ranking as follows:
0 – No defensive players around, nobody blocking the shot
1 – Light defensive pressure, no direct tackle but a player stood a few yards away causing some part of the goal to be blocked
2 – Low defensive pressure, a player a few yard away but could be sticking a leg out looking to make a block
3 – Medium defensive pressure – Close contact with a defender, a player blocking the ball from close range, s player holding onto the shirt but behind the man
4 – High defensive pressure – Many defenders crowding around the shooting player, Tackles being made as the shot is taken, very close contact when jumping to meet a header
5 – Intense defensive pressure – a player being held while taking a shot, many players all making tackles together giving very little room for a strike, a player crowded out when challenging for a header
With those defensive pressure rankings, I found the average shot in the SPFL this season has a defensive pressure of 2.04. However, St. Johnstone have an average defensive pressure of 2.14, meaning they are typically getting more pressure on shots taken than the average SPFL shot, further evidence that the Saints are allowing a lower quality shot than much of the rest of the Scottish Premiership.
Tommy Wright clearly has made an organized defense the heart of his St. Johnstone team. The numbers point to another organized back line that keeps it’s shape to prevent opponents from taking quality shots and those shots they do allow have plenty of defensive pressure being applied to them. Wright has the Saints organized and you would have to wonder how long until a bigger club either here in Scotland or elsewhere notices his success with St. Johnstone and want him to bring the same defensive organization there. Until then, Saints supporters will enjoy the continued success Wright has brought their club.