written by – Rangers Report
For an introduction to applying PDO to football, please read the introduction here.
Presenting the elements of PDO can begin to give you hints of which teams may be outperforming their expected outcomes based on having a save percentage that is higher than the norm, or if their finishing touch is off the charts. In both cases, regression to the average is expected – either in the short-term or in the long-term. Sometimes you don’t see the regression until the following season & sometimes it happens mid-season as a team’s luck begins to run dry.
I recently stumbled upon Carolyn Wilke’s graphs in her analytical coverage of hockey. Wilke, who covers the Dallas Stars for her blog Two Bearded Ladies, has a knack for labeling statistical outputs that really resonates. For example, teams that have abnormally high save percentages have been deemed teams that need to Hug their Goalie.
So I figured that it would be helpful to apply her labels for the elements of PDO to the Scottish Championship.
Save percentage is along the vertical axis, while shooting percentage runs along the horizontal axis.
- The average PDO is in the center with a Sv% of 0.692 & a Sh% of 0.303.
- Wilke labels the teams to the upper right of average as being teams that are Too good to be true? These teams have a high PDO & you would assume that their success rates would regress. However, I have added the question mark to the label because if you couple PDO with other indicators of success like Expected Goals Ratio or Shots on Target Ratio, you can pinpoint which teams may actually just be too good for the current level of competition. In a recent post, we correlated xG ratio with PDO & determined that Rangers & Hibs were indeed good enough to sustain their ‘good luck’. It was also determined that teams like Falkirk & Raith Rovers were more likely to see their form regress. Raith’s PDO has already began to dip as their success rates have begun to get closer to the norm. Falkirk’s PDO has actually increased & it will be interesting to see if they can sustain that success & truly compete with Rangers & Hibs. Falkirk is scoring on 41% of their shots on target & their goalie is saving 78% of the shots on target. Both are much higher than the norm….are they too good for the competition or just too good to be true?
- Wilke labels the teams to lower right of the average as having the Midas Touch. Their high shooting percentages are driving their success & indeed Dumbarton is scoring on 34% of their shots on target which is nearly on the level of a team like Hibs. However, their league worst save percentage (0.538) really highlights a major weakness in their lineup.
- Morton is the only team in the upper left hand side of this graph, & Wilke suggests that they should Hug their Goalie. Morton’s shooting percentage is significantly lower than the average (0.231) but a league best 0.815 save percentage is keeping Morton in the middle of the league table. The goalkeeping tandem of Derek Gaston & Grant Adam have been critical to any success Morton have had this season.
- Teams to the lower left of average may just be victims of Bad Bounces. Luck has not been on the side of teams like Livingston & Queen of the South as both of their elements of PDO are below average. For a team like Livingston, their overall save percentage was dragged down by poor goalkeeping early on in the season & have seen their PDO increasing in recent weeks as Marc McCallum has taken over in goal.
- Alloa is just really, really bad.
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