The Stanley Cup Final between the Boston Bruins and St. Louis Blues has gone back and forth between games. Each offensive spurt has been met with a counterpunch. Each loss is followed by a necessary adjustment. No real fireworks (yet), though plenty of players are trying to antagonize opponents. (Exactly how many David Perron wrestling matches have we seen in front of Boston's net? Our unofficial count is three.)

The result? A series tied at two games apiece heading back to Boston for Game 5 on Thursday. Here are seven observations through four games, both on how this series will shake out and how it will affect the NHL on a bigger-picture scale.

This series might be decided by the availability of Boston's defensemen

The Bruins have already been without starting defenseman Matt Grzelcyk (concussion protocol), which has thrust John Moore into the lineup. Now they might be primed for an even bigger blow: losing Zdeno Chara for the rest of the series.

The Athletic reported that Chara suffered a broken jaw after taking a puck to the face in Game 4 -- in which he was not cleared to return for the third period -- and the Bruins should provide a more thorough update after the captain meets with doctors in Boston. Chara had been averaging nearly 22 minutes per night in the postseason and was a big factor on Boston's penalty kill, which has been excellent. (The Bruins recently had a string in which they killed off 19 consecutive power plays, spanning the Eastern Conference finals and Stanley Cup Final.)

"This matchup is not good with Z out, let's face it," coach Bruce Cassidy said Tuesday. "[The Blues] are a big, heavy team, so we lose that element. But someone else is going to have to step up, and I think we can do it as a group."

There's a chance Grzelcyk can return in this series. Meanwhile, Cassidy floated the idea of dressing seven defensemen because there is no obvious singular replacement for Chara. Steven Kampfer is the most experienced reserve the Bruins have available, and he's played in two playoff games so far, but he's a right-shot defenseman, not left like Chara, so that messes up some pairings. The Bruins could turn to youngsters: Urho Vaakanainen, Jakub Zboril and Jeremy Lauzon are all left-handed shots, but they have very limited NHL experience (20 combined games among them). This is an area where St. Louis can exploit Boston.

Special teams matter

A team can win a Stanley Cup without exceptional special teams; in fact, the 2011 Bruins had a pretty crummy power play. The Blues have been, at times, a better team at 5-on-5 but lost two of the first three games due to taking a combined 14 penalties (and also being without one of their primary penalty killers, Oskar Sundqvist, in Game 3). Boston's power play is historically good and has the power to deliver big punches. Look no further than Game 3, when Boston went 4-for-4 on the power play ... on only four shots.

The Blues' power play, meanwhile, was almost a liability for them in the Game 4 victory; they couldn't sustain any momentum from it and even gave up a short-handed goal. Credit the Bruins for having an underrated penalty kill, but it's clear that special teams will matter in the outcome of this series.

Binnington, Johansson, Krug will get paid

Rookie sensation Jordan Binnington has been the avatar for the Blues' unflappability in the second half of the season. There's no way St. Louis makes it to this point without the goaltender, and he's up for a new contract this summer. The problem for St. Louis is that there are no obvious comparables for Binnington's next deal. The Blues obviously want to keep him around, but as a by-product of their own success, they'll just have to shell out more money to do so. It's likely the sides settle for a bridge deal if they can't agree on terms.

Boston orchestrated two of the season's best trade-deadline moves in acquiring Charlie Coyle (nine goals these playoffs) and Marcus Johansson (11 points in 19 games). Johansson is a particularly interesting case because he becomes an unrestricted free agent this summer. His current contract (a shade under $4.6 million this season) was viewed as a value for a top-six forward, but he wasn't producing like one. The Bruins have used Johansson on the third line, and he's flourishing in that role. That could inspire teams to reexamine where he belongs in the lineup come next season. But regardless, his contract value will be much more than what would have been offered a few months ago.

Torey Krug enters unrestricted free agency after next season. Boston knows Krug loves to play for the Bruins, but the team also knows he's due for a raise from the $5.25 million he's making. The 5-foot-9 undrafted defenseman broke into the league because of his offensive prowess, but over the past few years, he's emerged as a standout all-around defenseman and should be paid as such. The Bruins will likely figure something out, but this playoff run has certainly raised Krug's profile. Other usual big spenders might try to get in on the action. It's worth wondering if Krug, a native of Livonia, Michigan, might consider the Detroit Red Wings. On a rebuilding team with new general manager Steve Yzerman, Krug would instantly become the No. 1 defenseman and a piece around whom to build.

A new trend in goalie workloads?

The two goalies left standing in the Final weren't overworked during the regular season. The Bruins lightened Tuukka Rask's load (he also missed some time with injuries and a personal absence) as the Finn started only 45 games this season -- a far cry from his 67 starts in winning the 2014-15 Vezina Trophy. It helped that Boston has an ultracompetent backup in Jaroslav Halak.

Rask was the most outstanding goalie in the first three rounds, leading Boston to the Final with a .942 all-situations save percentage. "I don't know exactly how many games we were going to play Tuukka [in the regular season], but it was definitely going to be less than a typical No. 1," Cassidy said earlier in the playoffs, noting he preferred somewhere around the 50- to 55-start range. "It's been lower than that. I think it's helped him. I don't know how much -- only he can answer that."

Binnington comes in at 30 starts, since he didn't make his debut until late December. That means we'll have the seventh consecutive season with a Stanley Cup-winning goalie making fewer than 60 starts (Braden Holtby led Washington last season after also seeing a decrease in his usual responsibilities, in part because Philipp Grubauer was challenging for the No. 1 role).

Considering teams often try to emulate the most recent Cup winner, we'll start to see teams reexamine their practices. This feels particularly pertinent to a few teams on the cusp. The Vegas Golden Knights, Winnipeg Jets, Toronto Maple Leafs and Montreal Canadiens all overworked their starting goaltenders (60 or more starts for each of them) and might begin looking at contingency plans to lighten the load as soon as next season to keep those guys fresh for playoff time.

There's still a place for heavy hockey

At the end of the Western Conference finals, Sharks coach Peter DeBoer made this observation: "I think the two hardest, heaviest teams are in the Final. Everyone talks about skill and all the small players, and there is room for that, but I don't think it's an accident."

DeBoer is onto something. Yes, the league has been trending shorter and speedier (which was spurred, in part, by the Penguins' back-to-back championship teams), but there's still a place for heavy hockey, especially in the playoffs. The Blues are a tall team -- they have eight players who stand 6-foot-3 or taller. Even though Boston, on average, is a smaller team, the Bruins play a tough brand. Replay any of the first four games, and there's a good chance you'll see these teams beating each other up and shoving each other around.

What does this mean going forward? That the big guys won't be phased out as quickly as we thought. Patrick Maroon had a somewhat disappointing regular season but has been an important presence in the playoffs. In fact, Maroon and the Blues' playoff run could directly boost the value of some other aging, bigger-bodied vets looking for new deals this summer.

Get ready for more retreads

We know what you're thinking: NHL GMs haven't exactly been creative with hirings in the past. In fact, five of the head-coaching vacancies this year were filled by men who already had NHL head-coaching experience.

But Cassidy and Craig Berube's respective successes are going to mean this trend won't end anytime soon. Consider that when Berube was fired in Philadelphia in 2015, his future as a head coach looked bleak. His two-year stint was unmemorable, and then-GM Ron Hextall categorized Berube as a coach who couldn't get the most out of his players. The Blues gave Berube a chance when they needed a replacement in the middle of this season. He maintained a similar style, and this time it worked (or the circumstance was right). Berube instilled the right confidence to help his players out of a funk. What's more, people in the league have been lauding Berube for the way he guided his team past the hand-pass fiasco in the Western Conference finals.

Cassidy was also a flameout in his first stint behind the bench. Much younger and in Washington, his tenure ended because he was clearly out of his depth. He lost the locker room and struggled to communicate with some players. "I was young. I had really no NHL experience," Cassidy said recently. "So you walk into an NHL locker room and there's still a little bit of awe in that." He rehabbed his reputation as an assistant, and then in the AHL, and appears much more prepared this time around.

Seeing these two coaches thrive will likely inspire the next round of hiring, so chin up, all you coaches out there looking for a second chance!

All is quiet now, but expect some officiating reform

With the exception of Berube complaining that his team was getting called for too many penalties, we haven't heard too much about officiating in the Stanley Cup Final so far. Let's not forget, though, that officiating controversies consumed everyone -- in and out of the league -- for the first six weeks of the playoffs. So much so that commissioner Gary Bettman showed rare candor in his pre-Stanley Cup Final news conference, explaining he was just as frustrated as fans by missed calls and rule-book loopholes when it comes to video review.

"It would be good if I kept my head from exploding," Bettman said of the uncalled hand-pass play that marred the San Jose-St. Louis series.

So even if we make it through this final week without any controversy, don't think the conversation about expanding video review will go away anytime soon. Change should come next season in some form. The competition committee is scheduled to meet June 11 in Toronto, and the next GMs meeting will be June 20, ahead of the draft in Vancouver, British Columbia. A resolution could be announced shortly after that.