Every so often, we tell @statsrespecter that he should write a blog post or article instead of a twitter thread. Today, he and Kate have caused an article to exist out of, well, a twitter thread.

Here’s a closer look, inspired by Ryan Lambert’s must-read takedown of the Nashville Predators, at some of where things are going wrong for the Predators.

Nashville is continually portrayed as playing too wide-open, giving up too much defensively for the sake of unfettered offense. This narrative kicked into high gear when Poile traded Shea Weber for P.K. Subban, and it hasn’t really eased off since.

The truth is that Nashville ranks tenth in 5v5 CA/60, sixth in CF% (shot attempt share). They rank fourth-best in limiting quality against (as represented by xGA/60) and seventh in quality share. They are not just “good” at limiting offensive chances, they are elite. That narrative doesn’t hold up.

And the other statement, “wide-open offense,” also doesn’t line up with the numbers. We’ve been through it ad nauseam—Nashville takes a ton of shots, but their average shot distance is too far (23rd in the NHL, according to Moneypuck’s data) and they don’t generate enough quality.

Lots of shots (fifth in CF/60)

Low quality (16th in xGF/60—they’re outside the top half of the league, despite generating shots with the best of their peers)

Follow so far? Nashville is good defensively, they limit shots and chances against, they take lots of shots of their own, but offensively they aren’t putting themselves in a position to succeed.

The funny thing here is that you can win with this formula. The Winnipeg Jets, Boston Bruins, and St. Louis Blues are all teams winning despite generating very poor quality for (31st, 30th, and 29th respectively) by keeping up elite defensive stats—well, the Bruins are keeping up elite defensive stats (fifth-best xGA/60 in the league), anyway. So what’s different for the Predators, and why aren’t they able to get away with it when those other teams are? A couple of things.

First is goaltending.

Among 58 goalies with at least 300 minutes played at 5v5, Pekka Rinne is 35th in goals saved above average (GSAA), 35th in goals saved above expectation (GSAx), and 34th in Fenwick save% delta (dFSv%). Juuse Saros, meanwhile, is 55th in GSAA, 53rd in GSAx, and 58th in dFSv%.

GSAA looks at the total number of shots on goal a goalie has faced and applies the league-average save percentage to those shots, without really taking shot quality into account. It’s a brute-force method of looking at what a goalie is doing that works even if you don’t have detailed shot locations.

looks at the total number of shots on goal a goalie has faced and applies the league-average save percentage to those shots, without really taking shot quality into account. It’s a brute-force method of looking at what a goalie is doing that works even if you don’t have detailed shot locations. GSAx is the fancier/more sophisticated version of that. It’s a comparison of the number of expected goals—based on shot location and other variables—the goalie has faced to the number of goals the goalie actually allowed.

is the fancier/more sophisticated version of that. It’s a comparison of the number of expected goals—based on shot location and other variables—the goalie has faced to the number of goals the goalie actually allowed. dFSv% is the difference (delta, sometimes written Δ) between the percentage of Fenwick (unblocked shots) the goalie has saved and the goalie’s expected save percentage on those same unblocked shots, again using shot location and other variables to calculate the likelihood that each of those shots might turn into a goal.

All of these stats attempt to remove the “but the team in front of them...” argument by using regression to say “history suggests you should save this shot, in this context” or, in even simpler terms, “a league-average goalie makes this save.”

Rinne has been in the bottom half of goaltenders in regular rotation this season in all stats. Saros is one of the four or five worst regular goaltenders this season in terms of his results. Take into account what I’ve already said: the team is doing a good job limiting volume of chances against, but when a good chance occurs, it’s going in.

Saros in particular has struggled there—he has the worst high-danger save percentage (HDSV%) in the league. So to the observer that’s saying “Saros had no chance at that,” maybe there’s some merit to the argument: the goals against Saros have mostly been on quality chances. He is still getting regular starts in the NHL, and is still the Predators’ expected future starter, so you’d like to see him stopping more of those high-quality chances, but he’s struggled in a reasonable and understandable way.

Rinne, on the other hand... He has the third-best HDSV% in the league; he’s making the tough stops. However, he ranks 54th in medium-danger save percentage and 23rd in low-danger save percentage. The goals Rinne are giving up are ones he should be stopping, based on his past performance. So both goaltenders are struggling in different ways, and it’s killing the Predators.

Back to the Blues, Bruins, and Jets. Connor Hellebuyck is my runaway Vezina pick; he’s absolutely carrying a dogs*** team. Tuukka Rask and Jordan Binnington are both in the top quarter of the league in most of the stats we’ve discussed. The Bruins’ shutdown defense is getting rewarded, the Blues’ mediocre play is getting bailed out, and the disaster that is the Winnipeg Jets is being contained on a nightly basis thanks to heroic performances from Hellebuyck.

Now, NSH’s goaltending is a problem—but it’s not the only one.

I’ve gone on and on all season about how only one line is generating scoring chances and converting the way it should, and it’s not the line that should have to carry the offense. What Craig Smith, Nick Bonino, and Rocco Grimaldi have done as a line is admirable.

The Filip Forsberg - Matt Duchene - Mikael Granlund line has also been good, but hasn’t been together as much, due either to Forsberg or Granlund being injured or to the coaching staff putting JOFA back together with catastrophic results (84th in xGF/60 of 140 lines with at least 60 mins ES TOI—that’s in the bottom half of regular lines, and these players are too good to be playing that badly for the Predators).

Something else to consider is the amount of goals scored vs expected: for as good as the third line is at generating quality, it’s still outkicking its coverage more than any other line in the league outside of Marchand-Bergeron-Pastrnak, with 10.2 goals above expectation. Nashville doesn’t have a single line that’s scoring fewer goals than their xGF, which could suggest that the shooting percentages might still be inflated and there might be another letdown coming.

In sum, Nashville has a few things working against it right now, but, in spite of the number of goals they’ve been allowing, the defensive execution or structure isn’t one of them. The primary culprits are production, with only one line in the top 30 in GF (the third line) and mediocre goaltending.

The “why” on the offense’s struggles is a topic for another day and is harder to hang on individual players, but the bottom line is this: if Nashville is to overcome lengthening odds and make the playoffs, they’re going to need much more from Rinne and Saros.

[Ed.: We’re planning to offer some continuing analysis of what’s happening with the offense, as well as overall—both statistically and with more X’s and O’s type stuff—over the next few days. Stay tuned!]

Statistics referenced are from naturalstattrick.com, evolving-hockey.com, moneypuck.com, and the author’s own work.