Propositions

The playoffs are imminent. Our New Jersey Devils, for the first time in forever, will be competing. And I mean competing, not the out-in-five whimper we saw in 2018. I wanted to take a look at Devils goalscoring entering the playoffs, particularly which players we might expect to stand up and take responsibility in big moments. Who are big-moment Devils? On the other side of the same coin, goaltending will make or break any team’s playoffs. I therefore look at goaltending using the same sort of methodology as for the scorers.

I call this methodology marginal goals. In economics, marginal refer to the next unit, basically considering the individual incremental impact of this next unit: if we are at x and the marginal unit puts us at x+d, economists are interested in this d: the difference between where we are now and where we were before. In the context of hockey, if we are at x and a goal is scored, what is the d of this goal? What is its marginal impact, in the immediate context in which it is scored? When a goal is scored, basically what happens is that the goalscoring player adds one to his season total, which is then used to evaluate that player’s scoring ability at the end of the year. But it should be more granular than that. A goal when down by one with two minutes to go is not the same thing as a goal when up by five after the second period. This difference is what marginal goals tries to capture, at the time of the goal being scored: what is the individual impact of that particular goal in its wider context.

The Devils are a goal-scoring team. They sit 6th in the NHL in all-situations goals per 60, and have a plethora of potent individual goalscorers. Jack Hughes is a 40 goalscorer in his third NHL season. Jesper Bratt and captain Nico Hischier have both hit 30. On the backend, Dougie Hamilton tied the single-season record for franchise goalscoring among defensemen with his career-best 22nd. However, what does this actually mean? All other things being equal, more goals are of course better than fewer, but if we consider only goals and the impact of goals, has Jack contributed twice as much as Dougie, 33% more than Nico and Bratt? And what about guys like Mercer, Tatar and Sharangovich? They have 27, 20 and 13 goals apiece and represent depth scoring on the Devils. How can their contributions be compared to, say, Jack’s? These pure goalscoring numbers say nothing about the context wherein they were scored: looking at these stats, one would think that a game-winner with a minute left in regulation is worth as much as an empty-netter when the team is already up by two.

Similarly, goaltenders save shots and prevent goals. Vitek Vanacek has been the main man in net for the Devils this year and has conceded 119 goals, compared to the 60 for Blackwood and 32 for Schmid. But again, there is no context: all other things being equal, conceding a goal when up by five is worth the same as a goal conceded when up by one according to these raw numbers. There are vast amounts of statistics available, quantifying the performance of goaltenders, but these all consider the saves they make, not the goals they allow. For instance, of shots that become goals, do you know what the expected goals are, on average, on those shots? Neither did I, yet this feels like a highly significant aspect of goaltender evaluation. We complain when Blackwood gives up a softy, but how can we quantify this? Does he really give up more softies than Vanacek and Schmid, for instance? And we talk about backbreakers, goals that shift momentum or put the team in a hole. How can we quantify this?

These are the sort of questions I will attempt to answer here. This is a two-part article, with the first part on goalscoring in the rest of this piece, and the second part to be published tomorrow on goaltending.

Clutch Goalscoring

These questions, for goal scoring and stopping alike, are contextual. A goal can only be considered relative to the game it was scored in, and the phase of play that it was scored in. The metrics I propose for these questions are based on a goal’s impact on winning probabilities: if Hughes scores a goal, or Vanacek lets one in, this will change the probability of the Devils winning that game. This change in winning probability I denote dW%. Basically, at a given moment in time, the Devils will have a certain chance of winning the game. Going up or down a goal will change this likelihood, and dW% measures the size of this change. For goalscorers, contributing goals with high dW% is a good thing, as they give their team a better chance of winning. For goaltenders, conceding goals with high dW% is a bad thing, as they are throwing away their team’s chances. MoneyPuck, throughout all NHL games, at all times, provide the probability of each team winning the game, derived using their models which use run-of-play statistics to evaluate the relative strengths of the two contesting teams. The following is how this probability evolved throughout the Devils-Capitals game the other night.

The game started off as 60-40 Devils, before swinging the Capitals’ way by 50% or so when they jumped into a three-goal lead. Erik Haula scored at the end of the first, giving the Devils a roughly 7% greater chance of winning, and so on with the Caps going up by three again before the Devils gradually clawed their way back. Notice how when the Caps were in the lead their probability of winning slowly increased when nothing was happening. Note also how Dougie Hamilton’s goal made it 50-50 while Luke Hughes’ overtime winner alone was worth 50%.

Here is the trend from another game, Tampa Bay versus Arizona from the middle of February. This game was scoreless through regulation and overtime, with the Coyotes winning in the shootout.

Note how Tampa started off with a 65% or so chance of winning, which then converged towards 50% as the game remained scoreless, hitting 50% by the time overtime started.

Why are these evolutions relevant? Well, consider the drop in the Capitals’ probability of winning following Erik Haula’s goal. This is an increase in the Devils’ chance of winning, dW%. As you can see here:

MoneyPuck provides the exact dW% for each goal, where this time Haula increased the Devils’ chances by 7.26%. If we consider this in the context of the standings, Haula gave the Devils a 7.26% greater chance of getting two points in the standings. We can then say that this goal was worth 0.0726 * 2 = 0.1452 expected standings points. I call this standings-weighted goals, or SWG. If any goal increases the Devils’ likelihood of getting two points in the standings by dW%, that goal would be worth an SWG of 2 * dW%. There is one exception to this rule: overtime. If the Devils reach overtime, they have already gained one point in the standings, meaning they are only playing for one incremental point. As we saw in the Tampa-Arizona example, in overtime, both teams have a 50-50 chance of winning. So in effect, the Devils will have 1.5 points in expectation, 0.5 expected points from the overtime. As such, any goal in overtime is worth 0.5 SWG, rather than the 2 * 0.5 = 1 SWG one would otherwise obtain. You could argue that playoff overtime goals are not the same as regular-season overtime goals, with the former being exponetially more important, and that thus underweighting regular-season goals when using SWG as a metric for playoff-goalscoring competence might not be advisable, since the ability to score OT goals should translate to big-time performance in the post season. However, since regular-season OT goals are less important, the ability to score them is also less important, and we can imagine that the two effects cancel out.

The following tables shows the Devils goalscorers this season ranked according to goals, SWG, and average goal weight AGW = SWG / G: the total number of standings points a player’s goals has contributed in expectation divided by the number of goals that they have scored. The name average goal weight seems appropriate, given that a high SWG/G implies that the player has possibly scored relatively few goals, but that those goals have increased the Devils’ standings points significantly. Basically, each goal is more important than the average goal scored by the Devils. The first table is sorted by SWG, the second by AGW.

Note that players such as Bahl, Smith, Foote, Holtz and Luke Hughes are omitted due to being fringe players or not having scored more than a goal or two this year. For Timo Meier, I have only included his goals for the Devils. Fellow new player Curtis Lazar has been omitted entirely. I do not include their stats from San Jose and Vancouver simply due to the fact that they played for other teams, meaning I would have to go through all of their games on MoneyPuck to gather the dW% for each of their goals. Ideally, MoneyPuck would provide this data, and then I would be able to not only look at their stats, but perhaps also look at guys who have been in the playoffs before: what sort of dW% distribution does Palat have for his playoff goals in the past three years? And Erik Haula? Alas, not now, but perhaps in the future.

Unsurprisingly, the top-five SWG-scorers are also the top-five goalscorers, where the first point of interest is right at the top, where captain Nico Hischier has more SWG than Jack Hughes, despite the latter having scored twelve more goals. Jack has grabbed the headlines, but Nico’s goals have, at the time of him scoring them, done more to help the Devils in the standings. In fact, looking at Nico’s AGW, he is near the top of that ranking as well: our captain is of that rare breed which scores a lot of goals and all of them are important. I am keeping my eye on him when the going gets tough.

Below these five guys we have a second tier with Haula, Wood and Tatar, who, along with Palat (who has been injured for large parts of the season) are the Devils’ depth scorers. Tatar has the most goals in the group by a stretch, but has contributed only the third most SWG. In terms of AGW, he is in the same group as guys like Sigenenthaler, McLeod and Bastian, hardly guys you would consider (even prospective) clutch playoff guys. Looking at this, I would not put my money on Tatar to get the OT goals come post-season, but he may add an empty netter or two. The same, but to a lesser extent, goes for Sharangovich, whose goalscoring is obviously as streaky as it gets (when he is in the lineup) and whose SWG and AGW are similar in style to Tatar.

The AGW-ordered table provides some surprises. At the top we find Ryan Graves, who has scored 8 goals this year and has made them count. Back in February he scored a last-minute winner against Columbus and early in the year he tied it very late against Edmonton. It is not like those goals were blasts from the point, he was highly involved in the play, scoring from the slot on both occasions, so I would not be surprised if he came up with a big moment in the playoffs.

At the top of the AGW rankings, we have all of the main goalscorers: Hischier, Hamilton and Meier are in the main top group, Mercer, Bratt and Hughes are just behind. It makes little sense to discuss Timo Meier in SWG terms, however, his AGW is pretty good, as is his general goal output, scoring nine times in his 21 games for the Devils at a respectable 35-goal pace over 82 games. Given that it took Timo a while to get going, I am completely at peace with the trade. I think he has done a good enough job to have high expectations for him in the playoffs.

The three main guys, on top of Graves, who have scored big goals on average this year are Haula, Wood and Palat. I am hesitant to put Palat in the group, as he is a level down in AGW, but I do think he belongs there. Clearly he has not been as good as he can be, as he was in past playoff runs, in his first season with the Devils. However, he has been injured and with it being his first time on a new team I can forgive him. Considering this, that he has still had some big goals in the regular season I see as a massive positive and a hint of what is to come. Before his recent hot streak, Erik Haula has struggled, as we all know, to score at all, so for him to be in this group is slightly surprising. The lion’s share of his big goals have come recently, so he is trending in the right direciton. His comments throughout the season, and his pedigree, never having missed the playoffs in his career, show that he is extremely motivated, so when we get to playoff time I would not be surprised to see him contribute, especially if Ruff sticks him with Jack. Finally, Miles Wood is going to be in the lineup come playoff time. I would not have him in there, you would probably not have him in there, but you can bet your life Ruff will have him in, and lean heavily on him once the games get going. As such, perhaps some minor consolation would be that, of the goals he has scored this year (he started off on fire, but is as streaky as Sharangovich), they have been important ones. That Edmonton game early on in the year comes to mind, where he single-handedly got the Devils back from a two-goal deficit.

We know that Hughes, Hischier, Bratt, Mercer, Hamilton and Meier are going to score, are going to have to score, in the playoffs if the Devils are going to make noise. What these numbers from across the year tell me is that we can expect Haula, Palat, Wood and possibly even Graves to come up with the goods in the big moments, but that we should perhaps not wait up for Tatar and Sharangovich to do so.

Your Thoughts

What do you think of this analysis? This was only meant to be an initial probing into this style of analytics, looking at marginal goals, goals with context. Do you feel that there is something of value here? I was quite surprised to see Nico’s SWG out-do that of the 40-goal man and was also surprised to see Haula up there in the AGW rankings. Did these findings align with your expectations? Is there someone you think will defy these numbers?

Tomorrow I will publish an article looking at the Devils’ goaltending this season. Generally, goalie stats focus on saves, on goals that they do not allow, but I will look at the goals they have allowed to see what this says about their playoff credentials. Until then, thank you for reading and suppporting the site!