The Carlyle Effect Revisited: Randy’s WOWYs

Photo Credit: Brad Rempel/USA TODAY SPORTS

Back in 2014, I wrote an article about Randy Carlyle’s effect on Corsi for players on the Toronto Maple Leafs.  It was the end of Carlyle’s second full season behind the bench after taking over for Ron Wilson part-way, and it seemed like a good time to reflect on how the coaching change had affected possession.  The conclusion was stark: virtually every player who played for both coaches on the Leafs saw their Corsi fall, usually precipitously, after Carlyle replaced Wilson.  The effect was so strong it could be seen mid-season the year both men coached the Leafs for part of the season.

The Leafs have now finished their first full season with Mike Babcock behind the bench, roughly a year and a half after Toronto decided it was time to move on from the Carlyle era.  Since we’ve now got another coaching change to look at, I thought it would be a good time to revisit the idea and see if the Carlyle effect is apparent in reverse.

I’ve collected the 5v5 shot attempt ratio (or Corsi For %) of every player on the Leafs who played at least 20 games under Randy Carlyle in 2014-15 and at least 20 games under Mike Babcock in 2015-16.  That allows for a quick comparison of how CF% has changed over the previous year.  This method isn’t perfect; there are roster and linemate changes between seasons, as well as differences in deployment.  But it gives us a decent overview.

The change in possession between the two coaches is pretty apparent from this chart:

As you can see, other than Joffrey Lupul, every forward who played under Carlyle in 14-15 and Babcock in 15-16 saw jumps in possession, most of them quite large.  You might argue that most of what we’re seeing here is due to roster changes rather than coaching, but there’s a fairly simple way to test that:

What happens when we add in CF% under Peter Horachek, who took over from Carlyle mid-season?

This confirms what we saw in the first chart.  There’s a fairly consistent pattern here of players improving in CF% almost immediately upon Horachek taking over for Carlyle, and then the improvement continues under Babcock.  It certainly looks like Carlyle’s coaching was having a significant negative impact on possession.

We can look at the same numbers for the four defencemen who played at least 20 games under both coaches.

The effect is even more clear here.  Every defenceman who played for both coaches saw large jumps in possession after the coaching change.  Let’s add Horacheck in again:

The result is the same as it was with the forwards: Corsi improves dramatically mid-season once Horachek replaces Carlyle, and then goes up even more when Babcock becomes coach.

I think the charts give a nice visual representation of The Carlyle Effect, but it can be helpful to see the numbers too, so here’s a chart of the difference in Corsi between players who played for both Carlyle and Babcock:

The most important thing here is just how big the jumps in Corsi are.  Seven of the eleven players who fit my games played criteria jumped 6.8% or more in possession in just one season.  In fact, the only player who didn’t see a clear increase in their possession under Babcock is Joffrey Lupul, who faced frequent injury problems that made it difficult for him to find his game.

There’s no simple way to average out the effect among the players here because some of their minutes were played together.  But broadly speaking, it’s pretty clear that there’s a very large impact.  In the article that I linked in the opening, I estimated that Carlyle’s negative effect on possession was somewhere in the range of 5-7%.  Over the past couple of years, a lot of people have suggested that I was over-stating the impact, but I think the data I’ve collected here demonstrates that my original estimate was probably pretty fair.

That estimate was based on the difference between Carlyle (a bad coach) and Ron Wilson (a decent coach).  Babcock is better than decent, which is why it’s not too surprising that more than half of the players here saw jumps over 7%.  It’s impossible to positively identify the precise mix of factors leading to the improvements seen here; some of it is due to eliminating Carlyle’s negative effect, some of it is due to adding Babcock’s positive effect, and some is due to lineup changes.  But the overall result is pretty clear and confirms my conclusion from 2014: Randy Carlyle had a significant negative impact on his team from a puck possession standpoint.