Boston Bruins forward David Pastrnak celebrates his goal with Dmitry Orlov, Charlie McAvoy, Tyler Bertuzzi and David Krejci during the third period of a March 4 game against the Rangers in Boston.

On March 9, the Boston Bruins appeared to be on the road to an easy win over the Edmonton Oilers, building a 2-0 lead in the first period.

The B’s went on to lose, 3-2.

Two days later, the Bruins appeared to be on the fast track to defeat against the Detroit Red Wings, trailing 2-0 in the first.

The B’s went on to win, 3-2.

The two-goal lead. The most fragile lead in sports. Two-goal leads seem to go up in smoke faster than an Arizona Coyotes arena plan. 

But is the perception legit, or is it another one of those sports chestnuts along the line of baseball’s “Why does the player who makes the great play to end the inning always the first one up next inning?” or “Why does the guy always need just the little ol’ single to complete the cycle?”

Let’s examine it through both qualitative and quantitative measures.

• • •

On the qualitative, or human, end, you don’t need much prodding to get an answer in the affirmative. Both Colby men’s coach Blaise MacDonald and Bowdoin counterpart Ben Guite emphasized the importance of momentum in hockey, and how one goal can change everything. 

Just last month, MacDonald’s Mules trailed Hamilton 2-0 in the second period of their New England Small College Athletic Conference quarterfinal game, only to storm back and win 3-2 in overtime. 

“It is a 100% real,” said MacDonald, a veteran coach who previously helmed Division I schools UMass Lowell and Niagara. “Momentum can change very quickly in a hockey game. I think the difference between a two-goal lead and a one-goal lead in hockey is one shot. … If you have a two-goal lead in hockey, you’re almost desperate to make it three, and if you’re behind, you just want to cut the lead in half, and I think there’s a sensory behavior on each side of that, that has a big influence in the game.”

When coaching at UMass-Lowell in 2009, MacDonald’s River Hawks fell to Boston University in the Hockey East championship game. The Terriers went on to play in the NCAA final, where they trailed Miami (Ohio) 3-1 with a minute left in regulation. Faster than you can say “momentum shift,” BU scored two quick goals to force overtime, where it went on to win 4-3. 

“That one I always use as a reference point when my teams are down,” MacDonald said. “Anything can happen. As long as there’s time on the clock, you’ve got a chance to win this.”  

Guite is quite familiar with two-goal leads, and the ability to recover after letting one slip away. Playing for Maine in the 1999 NCAA championship against hated New Hampshire, his first-period goal helped the Black Bears grab a 2-0 lead, only for the Wildcats to eventually tie the score 2-2 and force overtime. 

Guite pointed out Maine’s lead could have been 3-0 — a second-period Dan Kerluke goal was overturned when video review showed teammate Jason Vitorino’s skate was in the crease — and the air went out of the Black Bears’ sails. Five minutes later, UNH forward Darren Haydar cut the deficit to 2-1

“All of a sudden, all that momentum we had goes out the window,” Guite said. “In the third period, we knew they were going to push, they scored a goal (by Mike Souza). But then once overtime starts, it’s like, “OK, next goal wins.’ But whatever happened before, it’s over. It doesn’t matter. 

“I thought it was good that we got it to overtime. Both teams were playing well and there were chances on both sides. I think overtime’s a good reset button, and I remember (coach) Shawn Walsh in the locker room said, ‘Hey, guys, we’re poised to make a play. We’re one shot away. That’s all we need.’”

Of course, Marcus Gustafsson scored in the extra session to give the Bears a 3-2 win and the national title, and many Mainers are still celebrating to this day.

“There’s no lead that’s truly safe in hockey, but I’d say the two-goal lead … the team that’s leading will mistakenly sit back a bit, and that’s where you get in trouble,” Guite said. “If we’re down by two, I’ll tell my guys, ‘Hey, we’re one goal away,’ and they’re going to start squeezing their sticks.”

• • •

Now let’s put human emotion aside in favor of some cold, hard numbers. 

First, let’s review every NHL summary from Jan. 1-March 15 in which a team held a two-goal lead in the first two periods. Out of 315 eligible games, 110 — 34.9% — resulted in a blown two-goal lead. So NHL teams lose leads about as often as the Chicago Blackhawks win a game: It’s not commonplace, but it’s not a rarity, either. 

Of those 110 blown leads, 55 resulted in a loss for the “choking” team and 55 resulted in a win, which confirms Guite’s remark about how what happened before doesn’t matter — it’s 50/50 once the score is tied.

In three cases, a team blew a two-goal twice in a game, and in two others, both teams blew a two-goal lead.

There also were three games in which a team built a two-goal lead in the third period — when the score had been tied — only to let it slip away. 

One important thing to remember: Through Wednesday’s games, NHL teams have scored 3.19 goals per game this season, the highest level since 1993-94, right before the New Jersey Devils trapped and zoned hockey fans into a collective coma. In all likelihood, more two-goal leads are lost these days simply because there are more chances for it to happen. 

In 2003-04, when teams netted only 2.57 goals per game, the percentage of lost leads was likely lower. It’s harder to surrender a two-goal lead when scoring two goals requires an act of God or Gretzky, as it did from about 1995 onward.

So what does this all tell us in the end? Two-goal leads don’t slip away every night … but don’t go to bed during intermission of a West Coast game thinking your team has a W in the bag, either.