A few years back, Mike Babcock talked about being a lifelong student of the game.

“I don’t know what it’s like in your business,” he said to a media member. “But in mine if you’re not getting better, you’re getting passed.”

You can see that philosophy in a lot of what Babcock has done over the past seven years. Including on the power play.

One of the things that analytically inclined people have muttered about, dating back to at least the early part of the century, is the refusal of coaches to move away from three forwards and two defencemen (3F2D) at 5v4. The argument in favour of using four forwards and one defenceman (4F1D) is simple: You score more goals in a 4F1D than you will in a 3F2D.

You’ll give up a few extra shorthanded goals, but the benefit more than outweighs the cost.

Year after year, a 4F1D produces better goal difference:

There are three obvious reasons for better outcomes with a 4F1D:

a) A 3F2D generally means a more conservative setup – with two players near the blueline – that will generally produce less dangerous shots.

b) The fourth forward you might stick on a power play is probably a better offensive player and shooter than the second defenceman available to you.

c) There’s probably some bias as far as first units being more likely to be 4F1D – although Matt Cane’s look at the issue a few years back suggested that even allowing for this in a back-of-the-envelope sort of way, 4F1D was better.

Despite this, NHL coaches have moved towards 4F1D at a glacial pace. Change in the NHL is a sort of Darwinism. Coaches hesitantly try new things and, if the adaptation proves advantageous to survival, they keep them. (If the adaptation isn’t advantageous to survival, or you have bad luck, or a team that the adaption isn’t enough to save, you get fired. It’s hockey’s equivalent of a lizard eating a bird, wiping out whatever unique adaptations that bird might have.)

But the 4F1D has proven hardy enough to survive the lizards and is gradually taking over the league:

Prior to 2012-13, Babcock was a power-play conservative, with his teams spending less time in a 4F1D than league average. In 2012-13, he began to experiment with a 4F1D, resulting in a Red Wings team that spent about as much time in 4F1D as league average. By 2013-14, he was a convert.

Babcock’s conversion seems to have been in response to his power play going in the tank. He had a dominant power play in Detroit from 2007-11, with Detroit’s +7.0 GD/60 being the best in the league at 5v4 in that period. No team generated more shot attempts per 60 minutes. But in 2011-12 and 2012-13, Detroit stopped scoring at 5v4. Although they were still pretty good at generating shot attempts (sixth in the NHL), their 5v4 goal difference fell to +4.8 GD/60, 22nd in the NHL. By 2013-14, Babcock had become a liberal, relying heavily on the 4F1D.

In the last two years, Babcock’s rolled back his use of the 4F1D, although he’s still well above league average. This comes with a caveat: He’s limiting his use of it in specific situations as opposed to a more general reduction of his reliance on it. While you generate more goal difference with a 4F1D than a 3F2D and teams with better goal difference win more hockey games, there are times when a goal against reduces the amount of points you can expect to take from a game much more than a goal for enhances it.

Babcock has backed off a bit as far using a 4F1D when leading in the third period. The effect of this is made more pronounced by the fact the Leafs have spent a lot more time leading in the third this year than in the past. (A cynic might suggest that the Leafs should worry more about extending their lead in the third, given the number of leads that have disappeared.)

But a move toward 4F1D isn’t the only way Babcock’s power play has evolved. Unsurprisingly, the 4F1D results in a higher percentage of the shots being taken by forwards and a greater number of shots overall: The puck is spending less time at the blueline because there are fewer people there. There’s a lot of variation between teams as far as how much they have their defencemen shoot, even comparing only a 4F1D and a 3F2D. Babcock used to run power plays that saw the forwards take around the league average of the unit’s power play shot attempts or less. That hasn’t been the case lately.

The 3F2D data above is subject to some sample size noise; as Babcock rarely runs the 3F2D any more, the data is noisier. Still, there are two spikes in the last three years, with the forwards getting a big percentage of the shot attempts. Where the change is really important is at 4F1D.

Babcock’s teams were five or six points below league average in terms of the percentage of shots attempted by forwards in a 4F1D from 2010-11 through 2012-13. In 2013-14, when he really moved to a 4F1D, his 4F1D had the defencemen taking about the same percentage of the shot attempts as league average, something that continued through the 2015-16 season. This year, he’s got the forwards 3.5 points above league average in percentage of shots attempted in a 4F1D.

That might not sound like much. However, the Leafs are on pace to attempt about 500 shots with a 4F1D this year. Moving the forwards’ share of those shots from five points below league average to 3.5 points above moves 40-50 of those attempts from the sticks of Nikita Zaitsev, Morgan Rielly and Jake Gardiner to the sticks of Auston Matthews, Mitch Marner, William Nylander, JVR, Nazem Kadri et al.

The attempts of the latter will hit the net more often and go in more often.

The effect of all these changes in formation and shot selection shows up in the average shot distance for Babcock’s teams over the past three years. His teams now tend to shoot from closer to the net than the league as a whole.

They’re also generating more rebound shot attempts per shot on goal than league average, something that Babcock’s team struggled with when he went to the 4F1D full-time in 2013-14. This might be an illustration of the influence of Leafs assistant coach Jim Hiller, who linked up with Babcock prior to the 2014-15 season. It’s hard to suss out the impact that assistant coaches have on things (and given that head coaches take the blame for all sorts of things they have little to do with, they might as well get unfairly credited) but Babcock has cited Hiller’s influence on his power play thinking repeatedly.

The benefit of Babcock’s changing approach is evident when the 2014-15 Leafs are constrasted with what’s going on this year. The 2014-15 Leafs were a 3F2D team that tended to rely on Tyler Bozak, Phil Kessel and JVR up front with a rotating cast of defencemen, the most commonly used of whom were Dion Phaneuf and Cody Franson.

Although the Leafs saw goals go in with Phaneuf/Franson on the ice with those three forwards, they weren’t so fortunate when they had other D in the mix. They ended up with a pretty lousy power play.

This year, the three most common Maple Leafs units are 4F1D. The shot distribution is much different.

There’s no parallel universe in which the Maple Leafs run 3F2D all year like a Babcock team of old, happily bombing away from the points and generating a properly mediocre 5.5 GD/60. The best you can do is look at their goals and think about how a play might have unfolded differently from a given situation if the structure and philosophy were different.

The Leafs scored a power play goal against the Senators recently where it’s easy to see how things might have been different:

The puck came to Zaitsev at the blueline. On many teams, the defenceman would step it into it here, or walk the line, looking to open up a lane to shoot. This would have been a particularly bad thing to try against Ottawa, the best team in the league at blocking/forcing shots from defencemen wide when facing a 4F1D, something that’s a hallmark of coach Guy Boucher’s teams.

After looking the approaching forward off with a glance to his right, Zaitsev zips a pass to Bozak. Bozak gets a shot through that’s deflected by van Riemsdyk and creates a rebound; Kadri cleans up the garbage. If, instead of Bozak down by the dot, Connor Carrick is standing at the point, his shot has further to travel before van Riemsdyk shoots, giving the Senators more time to react to the play. It’s pretty easy to imagine, watching this, how a team with defencemen who shoot more or using a 3F2D wouldn’t have gotten a goal out of the sequence. We know from the data that, on balance, teams get more goals out of a 4F1D than a 3F2D. Plays like this are why:

It’s not just power plays that would be easier to evaluate with a parallel universe, one where teams changed one variable or where we could play out a season an infinite number of times so as to wring the luck out of the results. It’s true of coaches as well. Babcock is universally acclaimed as a great coach, but he’s also had great teams in a lot of places.

How much credit do you give someone for a team accomplishing what it’s supposed to accomplish? You’re supposed to win with the Detroit Red Wings. You’re supposed to win with Team Canada. (You are not, however, supposed to win with the Lethbridge Pronghorns, a title that gets strangely overlooked when people talk about Babcock.)

This data provides evidence that Babcock is an excellent coach – one who’s always looking to get better, something he references often with the media. If the Leafs make the playoffs this year, their power play will be a big reason why: They’re comfortably in the NHL’s top five in most 5v4 categories and first in power play percentage (23.2 per cent) at the moment. (That latter number is the highest for the franchise in the past 27 years.)

There’s never a guarantee that doing things right will produce better results. But the evolution of how Babcock’s teams have approached the power play over the past seven years has made the success the Leafs are enjoying much more likely.