Should the Bruins break with tradition and start resting players?

In a previous post about the Bruins’ lineup decisions that you can find here, I suggested that the Bruins take advantage of the extra three men on their roster by resting players during the month of February.

If you’ve taken a look at the schedule, there are three back-to-backs on the road and a western Canadian trip. That is incredibly tough. And while my proposal seems taboo for hockey, teams in the NBA have been doing this for the last couple of years. In fact, coaches have been using this tactic so frequently as of late, they’ve forced the league to take action.

For most people, resting players is an easy call at the end of the season. Why play Bergeron the last game of the season when playoff position is settled, right? The question I, and NBA coaches, ask is why wait?

Take a look at the chart below from 538:

(A link to the full article is here.)

As you can see, it is becoming more and more popular to rest players before April in the NBA. There are even players who’ve been given rest in October.

Behind the trend is legendary San Antonio Spurs coach Greg Popovich. For those who are unfamiliar, he’s coached the Spurs for 22 seasons now, making the playoffs 20 years in a row, and has 5 NBA Championships. This man has given more than double the amount of rest days to players than any other coach since 2006.

“But this is basketball. What does this have to do with hockey?”

Exactly! This is basketball, a sport with far less contact and toll on the body. If NBA coaches are using this tactic to lengthen careers and keep their players fresh for the playoffs, why wouldn’t this work in hockey? After all, hockey players spend most, if not all, of the season with minor injuries.

Without a doubt, there are players in the Bruins’ lineup right now with a sprained wrist, strained MCL, or even just tightness. These are minor things a player is willing to play through, but things that put him at a greater risk of injury at the same time.

What would this potentially look like?

First, we need to set an approximation based on how much of a toll a player takes during any given game. I will do this by creating a GRIT stat, which takes into account how often a player hits, gets hit, and blocks shots. Those are potential injury areas that are featured on the NHL’s play by play.

I will also take time on ice into consideration, as this gives us an insight into other fatigue issues a player might face. All data is at 5v5 via Corsica, and you can see it below.

We can sort this group into four sections asking two questions:

• Does a player have a higher GRIT per 60 minutes than team average?
• Does a player have a higher Time on Ice per game than league average?

The players who answered yes to both are the ones we should prioritize to get rest. Adam McQuaid falls into this group, but we will consider him our rotation player, a role I will define later. The lineup regulars who fall in the Yes-Yes group are: Charlie McAvoy, David Backes, and Kevan Miller.

With McAvoy currently out with an abnormal heart issue, it may be even more important to ease him through February. For one, he’s a human being and it would be nice to take his health into consideration, especially when dealing with a heart issue. Also, considering he has some of the toughest usage on the Bruins, it can’t be easy to come back from injury into his normal role.

For Miller and Backes, it may seem weird to sit guys playing towards the bottom of your lineup, but they’ve been key players for the Bruins, and it is important to keep them healthy as well.

Our next priority is those who have a higher than team average GRIT per 60, but can’t say the same about Time on Ice. Those players are: Noel Acciari, Riley Nash, Sean Kuraly, and Tim Schaller. So again, bottom of the lineup guys, but they play a key role for the Bruins, and their minutes can take a toll on their body.

Our last group that we want to think about resting logs lots of ice time, but doesn’t have as much GRIT in their game as other players. Those players are: Brad Marchand, Brandon Carlo, David Krejci, David Pastrnak, Matt Grzelyck, Patrice Bergeron, Torey Krug, and Zdeno Chara.

The only lineup regulars that answer no for both questions are Danton Heinen, Jake DeBrusk, and Ryan Spooner. They will stay in our lineups no matter what.

So, let’s get back to the note about rotation players. Our rotation players are the guys who are healthy scratches when everyone is healthy. Assuming McAvoy is in full health, our rotation player at forward is Frank Vatrano, and on defense we have Adam McQuaid and Paul Postma. They will play any game in which a regular is being rested.

Below is the schedule for the Boston Bruins in the month of February. Let’s assume that 2 weeks for McAvoy leaves him healthy for the 5^th.

BostonBruins.com

Our rest days are back-to-backs and the western Canadian road trip. If we count both games of a back-to-back as a chance to get rest, we are left with 9 games where we can rest players. That works out fairly well. Look at our groupings by position.

Each of the 9 forwards can sit one game. Defensemen are a little more complicated, but let’s say each defenseman in our No-Yes category rests once, Miller rests twice, and McAvoy rests three times. This means, with a healthy lineup, only two regulars are out at one time. The strength of schedule is also poor on these days of rest, so the Bruins should still be able to get some wins. The only notable opponent is the Maple Leafs on the 24^th. We may substitute that game for the Flames on the 13^th.

What would be the benefit?

Using the GRIT statistic that was used to categorize players earlier, we can estimate how many points of potential injury a player would avoid by resting just one game, and we can sum these up to see the total impact in terms of injury.

With just 18 games rested, we can prevent 70 points of potential injury just at 5v5 alone. That may not sound like a lot, but let’s assume that there is a 0.5% chance of injury on any point of potential injury. Using a binomial distribution, there is a 29.6% chance of at least one injury occurring.

If we take that probability of injury even lower, let’s say 0.1% chance of injury per point of potential injury, there is still a 6.8% chance of injury that was prevented by resting players.

Let’s take this a step further. How much could the Bruins potentially save in terms of the dollar? Using cap hit per game, and the points of potential injury prevented, we can estimate the chance that an injury was prevented, and the cap hit lost per game of the potential player that we saved. Take a look below.

If the injury would only last one game, the Bruins save $9,386.49. If the injury would have been 5 games, the Bruins would save $46,932.45. That may seem like a small amount, but that’s because it is. With estimated salary expenditures above $82 million, it really is a small savings for the Bruins.

Does this outweigh the weaker lineup the Bruins would ice?

We are going to estimate again. A Win Above Replacement for a player in the NHL is about $4 million and there were 249.24 Wins Above Replacement last season among skaters. That is .2 WAR per game. That makes each game worth $810,536.

If we assume that resting players hurts the Bruins’ win probability 1% per game, it will cost them $145,896 for the 18 games. So, if the potential injury was just one game, it’s not worth it for the Bruins. It actually takes a 16-game injury for this to be a worthy investment for the Bruins.

Once thing worthy of consideration: with the Bruins so high up in the standings, is the game really worth that much to them? Let’s say games are only worth half as much to them now; if the potential injury is 8 games, then it would be worth it for the Bruins to rest their players. Perhaps games in which the Bruins play a non-conference opponent, which are only worth one-tenth to them, changes the point at which this is a worthy investment.

Final thoughts

The decision to rest players relies on how the Bruins value games and players in-house. Numbers like the injury rate or wins were just my estimations. The Bruins have their own.

Under my plan, with my estimations, it would not be worth it for the Bruins to rest players. However, there can be scenarios where it would make sense for a team to rest players. There is not a doubt in my mind the practice of resting players will spill over from the NBA.

The question is how long it will take.