For the last three full seasons, Tuukka Rask fell short of the Vezina Trophy-winning standard he established in 2013-14. The Bruins believed they had identified why Rask could not meet the threshold he set while backstopping one of the most loaded rosters of the Claude Julien era: inadequate backup goaltending.

Because Niklas Svedberg (2014-15), Jonas Gustavsson (2015-16), and Anton Khudobin (2016-17) did not play well enough to earn Julien’s trust, the ex-Bruins coach had to start his ace more than necessary. In those three seasons, Rask dressed for 70, 64, and 65 games, more than the 58 he recorded in 2013-14 with the reliable Chad Johnson as his backup.

So far this season, Rask is giving his bosses evidence their theory was wrong.

Rask is on track to appear in 55 games. It would be his lightest workload as a No. 1 goalie since a 45-game run in 2009-10 (excluding the lockout-shortened season of 2012-13). In 2009-10, as a 22-year-old, Rask shunted aside Tim Thomas, who would require hip surgery that summer.

This year’s lighter pace has not resulted in better performance.

It has been a lousy start for both Rask and the Bruins. Through 12 starts, Rask was 3-7-2 with a 2.89 goals-against average and an .897 save percentage. Rask was unavailable for two games against Vancouver and Buffalo in October because of a concussion, the result of when Anders Bjork checked him into the Mass. Pike during a full-speed practice collision. He has been playing behind a JV lineup, most closely affected by the loss of stay-at-homer Adam McQuaid, and compounded by a one-line attack up front.

But the numbers are the numbers. They are not good.

Bruins goaltending coach Bob Essensa has long considered one metric more important than others when gauging his charges’ performance: save percentage on scoring chances. That creates debate on what is and isn’t a chance, an argument repeated around the league in coaches’ offices. 

“It’s the one stat that, to me, is the best indicator of how our goalie is playing,’’ Essensa said during the Bruins’ annual coaching symposium in October. “For us, what’s a scoring chance? Typically, you’ll draw your home plate area. Not every shot in there is a scoring chance, clearly. Not every shot outside is not. So over the years, you kind of develop a good feel for what’s a scoring chance and what isn’t.’’ 

Essensa’s base is .800. It represents good, solid, trustworthy puckstopping. Essensa believes goalies win Vezinas when they reach .830 or better. Essensa starts to worry when his goalies aren’t stopping four out of five scoring chances. 

He should be worried.

Rask’s save percentage on scoring chances by Essensa’s definition is unknown. Corsica Hockey (www.corsica.hockey) uses high danger as its terminology to define the best degree of scoring chance by factoring shot location, type of shot, and rebounds as variables. According to Corsica, Rask’s high-danger save percentage this year is .771, which corresponds to his performance in the heavy-workload 2014-15, 2015-16, and 2016-17 seasons: .763, .745, and .758. 

In comparison, during his Vezina season, Rask’s high-danger save percentage was .827, not far off Thomas’s out-of-this-world standard in 2010-11 (.842). Consider the last six Vezina winners and their high-danger acrobatics: Sergei Bobrovsky (.857), Braden Holtby (.806), Carey Price (.849), Rask (.827), Bobrovsky (.837), Henrik Lundqvist (.834). Holtby in 2015-16 was a high-danger outlier, but the others were well into the sweet spot that Essensa considers trophy-winning stuff.

“We have endless numbers that get thrown our way,’’ Essensa said. “Endless analytics in terms of expected save percentage and goals saved above average. All these other numbers. But that’s the one: save percentage on scoring chances. It’s an easy one. You can do it at every level. That’s the one I’ll circle as most important.’’

This year, through 15 appearances, Bobrovsky is up to his old tricks again. The Columbus ace’s high-danger save percentage was .870, second best after Los Angeles’s Jonathan Quick (.873) among No. 1 goalies. By traditional metrics, Bobrovsky is doing quite well: 10-4-1, 2.16 GAA, .928 save percentage. It is no wonder Bobrovsky is the second-highest-paid goalie in the league ($7.425 million average annual value) after Lundqvist ($8.5 million). Price will take over top-dog status in 2018-19, the first season of his eight-year, $84 million extension.

In terms of salary, the NHL has yet to unlock appropriate goalie value. But comparing his contract and performance to his peers, Bobrovsky is being paid appropriately. Rask is not. His $7 million AAV, which runs through 2021, makes him the third-richest goalie this year after Lundqvist and Bobrovsky. By that framework, Rask is not meeting his contract standards.

He is not one of the three best goalies in the league. Rask might not even qualify as a top-10 goalie, not when his current competition includes Bobrovsky, Holtby, Lundqvist, Quick, Cory Schneider, Corey Crawford, Devan Dubnyk, Matt Murray, Martin Jones, and Pekka Rinne. Price, currently on the shelf, has been even worse than Rask, but the Montreal ace’s recent history defines his 2017-18 play as a blip, albeit a severe one.

None of Anaheim’s four goals against Rask last Wednesday was a softie. Kevin Roy scored on the rebound. Josh Manson’s fling from the boards went in off Zdeno Chara. Nick Ritchie cashed in a net-front dish from Antoine Vermette. Corey Perry stripped Kevan Miller and snapped in a shot off Derek Grant, who was screening Rask. 

But high-end goalies make saves they shouldn’t. The Bruins outshot the Ducks in the second period, 15-3. By the Bruins’ count, they limited Anaheim to a lone second-period scoring chance. Yet Anaheim scored twice.

Twelve appearances is a limited sample size. In theory, Rask’s numbers should improve as the Bruins heal and improve their chemistry.

But the team has enjoyed a light schedule so far. Rask’s workload has been on the dot. Khudobin (4-0-2, 2.35 GAA, .928 save percentage, .955 high-danger save percentage) has delivered results.

Rask will have three seasons remaining on his deal after this one. At his current level of play, it is an untradeable contract. The Bruins have no choice but to hope he’s in for a turnaround.

To the eye, Rask has not changed. He is one of the most fluid movers at his position. He makes saves look effortless. He is not a scrambler like Quick.

The numbers, however, indicate he is in decline. Rask’s play has created doubt about his long-term performance. Short term, there is no doubt about what he is: not good enough. 

SLOW DOWN FOR SAFETY

Time to consider injury deterrents

There are few general managers with depth charts that could accommodate the catastrophic cluster of injuries the Bruins have suffered. Even before 2017-18 is a quarter through, Don Sweeney has been without Brad Marchand, Patrice Bergeron, Anders Bjork, David Krejci, David Backes, Ryan Spooner, Noel Acciari, Adam McQuaid, Torey Krug, Tuukka Rask, and Anton Khudobin for at least two games. It is horrible luck, happening the same year the team limped through the playoffs with Krug, McQuaid, Krejci, Spooner, Brandon Carlo, and Colin Miller missing some or all of the first round. 

Aside from ill fortune, the Bruins’ bunching of injuries also reflects the danger of a league that has accepted speed as its primary virtue. Consider the nature of Bjork’s straight-line propulsion into Matt Martin, perpetually atop the league’s smackdown list. The rookie, the fastest skater on the team, was at full roar when Martin laid him out. A month earlier, Bjork was also rolling at full tilt when he was shoved into Rask, knocking the goalie silly with a concussion.

Injuries might be the biggest reason GMs cannot sleep at night. In some ways, GMs cannot control who gets hurt and at what time. The best they can do is build depth to counter injuries and provide a healing infrastructure — doctors, trainers, recovery apparatus, rest, nutrition — to promote swift returns to good health.

But they can also consider on-ice measures to plant speed limits back on the rink. The easiest fix is to bring the red line back. Bodies, regardless of their sturdiness, are simply not designed to walk away from high-speed, train-wreck collisions that involve players who have revved their wheels for the entire length of the sheet. Unless a slowdown happens, injuries will not cease. 

ETC.

Iafallo forces Cammalleri out

In a month, Alex Iafallo will turn 24 years old. In the NHL, it’s a ripe age for a rookie. 

Charlie McAvoy, in comparison, played his first NHL game when he was 19. But the Kings appear to have made a sound investment in the undrafted Iafallo, who signed as a free agent after completing his senior season at Minnesota-Duluth. 

The left-shot forward is not a point producer. Through 19 games, the Buffalo native had one goal and six assists. But he’s rapidly gained the trust of John Stevens. The first-year coach has given him a top-line role alongside Anze Kopitar and Dustin Brown. He’s averaging 17:19 of ice time, further proof of his reliability. Only Clayton Keller, Kyle Connor, and Yanni Gourde have higher workloads as rookie forwards. Keller and Connor are first-round picks. Gourde has five years of pro experience (Syracuse, Worcester, Kalamazoo, San Francisco, and Worcester). 

Iafallo’s unexpected emergence allowed GM Rob Blake to swap Mike Cammalleri to Edmonton for Jussi Jokinen. The Kings once projected Cammalleri for top-line duty. Instead, Cammalleri is now an ex-King, while the underachieving Jokinen gives Stevens more versatility if he can get his game firing again. Cammalleri is the better pure shooter. Jokinen, who managed just one assist in 14 games in Edmonton, can contribute in more all-around ways.

Iafallo not only pushed a veteran down the lineup but out of the organization entirely. Not bad for an undrafted 24-year-old.

Improvement expected in Toronto

Through 20 games, the Maple Leafs were comfortable in second place in the Atlantic, even with some of their best young players not meeting expectations. Mitch Marner, who’s seen time on the fourth line, had just two goals. William Nylander had four. In comparison, Marner pumped in 19 pucks as a rookie last year while Nylander scored 22. Bad luck is partly to blame for both of the sophomores’ downturns. Marner had buried only 5.7 percent of his shots, off the 10.8 shooting percentage he posted last year. Nylander was at 6.8 percent, well off his 10.7 percent rookie mark. Of the two, Nylander is generating more and better chances. Both should see their shooting percentages rise as the season progresses. Look out for the Leafs then. 

Historic stumble for Coyotes

The Coyotes hit the 20-game mark last Tuesday with a 4-1 loss to Winnipeg. The 2-15-3 Coyotes became the first team in NHL history to start the season without a regulation win in its first 20 games. The historic start gives Arizona the best odds of drafting generational defenseman Rasmus Dahlin with the first overall pick in 2018. It should also give GM John Chayka additional time to determine the future of Oliver Ekman-Larsson, who can walk for nothing after next season. The 26-year-old has no reason to stay unless Arizona opens its wallet, which, as a budget club, it is not equipped to do. A year-plus of Ekman-Larsson’s services could net the Coyotes a haul.

Dangerous situation

 An 8-2 Detroit beatdown of Calgary was roaring last Wednesday when a pummeling of another kind led to mayhem. The Red Wings, up 6-2 at the time, saw Luke Witkowski get the better of Brett Kulak in a third-period fight. The trouble began when Travis Hamonic took exception to Witkowski’s post-fight rag-dolling of Kulak. Witkowski had gone through Detroit’s bench and into the tunnel when he turned, stepped back onto the ice, and tried to engage with Hamonic. (Witkowski would be suspended for 10 games for his decision.) The ex-Islander got the worst of it when, while fighting Anthony Mantha, the defenseman tumbled through the door Witkowski had used to access the tunnel. It could have gotten really ugly. But linesman Scott Driscoll did well to defuse tempers by breaking up the Mantha-Hamonic bout and preventing other players from joining the scrap. Linesmen are the officials’ versions of fourth-liners: anonymous, hard-working, and important.

Niemi resurfaces in Montreal

Montreal GM Marc Bergevin dialed up the wayback machine by claiming Antti Niemi on waivers from Florida. Bergevin was the director of player personnel in Chicago when Niemi backstopped the Blackhawks to the Cup in 2010. Montreal goalie coach Stephane Waite held the same position in Chicago then. With Carey Price and Al Montoya injured and the Canadiens riding Charlie Lindgren, Bergevin didn’t want to take any chances. “You saw what happened with Vegas. They end up calling up a goalie from juniors,’’ Bergevin told Montreal reporters. “[Niemi] had experience. Steph knows him well. So we’re just being cautious.’’ Niemi started the year in Pittsburgh and was waived on Oct. 23. The Panthers put in a claim, only to waive Niemi last Monday.

Providence mourns Brown

Former Friar Drew Brown, who died on Nov. 11 because of bone cancer, did not play for Providence College during its title run in 2014-15. But Brown, who would have been a senior that year, served as inspiration for his teammates en route to their NCAA championship. Brown played a hard-hat style like best friend Noel Acciari. “He was a hunter and fisher, kind of a blue-collar guy,’’ said ex-teammate Tim Schaller. “That’s kind of the way his game was, too. That’s what the coaching staff was praising over there. Guys tried to play like Drew. When they won the national championship, he had a lot to do with that team. Even though he didn’t play, I think he was a big inspiration, a big reason they won that ring.’’ 

Loose pucks

Bobby Ryan, missing for almost a month because of a broken finger, returned to the Ottawa lineup last Thursday with ex-Avalanche Matt Duchene as his center. If Ryan and Duchene click, it would allow coach Guy Boucher to keep Derick Brassard on the No. 1 line with Mike Hoffman and Mark Stone . . . First-year Buffalo GM Jason Botterill will take his turn at participating in the franchise’s perpetual rebuild if and when he puts Evander Kane up for auction. Kane, unrestricted at year’s end, had 10 goals and eight assists through 18 games. The 26-year-old would be a good first- or second-line addition at left wing for any club seeking offensive punch. Considering the amount of teams who’d be in the market for Kane’s services, Botterill should be able to net significant futures . . . Former UMass Lowell puckstopper Connor Hellebuyck has seemingly rendered Winnipeg’s signing of Steve Mason irrelevant. Through 14 appearances, Hellebuyck was 10-1-2 with a 2.29 GAA and a .930 save percentage. The 24-year-old, under contract for $2.25 million annually, is providing better value than Mason (first season of a two-year, $8.2 million deal) . . . Rick Middleton will be honored at The Tradition, The Sports Museum’s annual bash at TD Garden, on Nov. 28. Middleton will be presented by Terry O’Reilly. For tickets, call Ashley Walenta at 617-624-1231 or visit sportsmuseum.org . . . After skating, shooting is the second-most important club in a player’s bag. Writing on such a fundamental act has led me, quite unconsciously, to use other shooting-related jargon that translates to hockey. Upon reflection, I’ve used these terms without contemplating their meaning. I will no longer write them. Words matter, even when they’re not written.

Fluto Shinzawa can be reached at fshinzawa@globe.com. Follow him on Twitter @GlobeFluto. Material from interviews, wire services, other beat writers, and league and team sources was used in this report.