If the Pittsburgh Penguins have given any NHL team a playoff blueprint, Sidney Crosby and his wanna-be tough guys have shown that a team can care too much. In their zeal to match machismo instead of goals with Philadelphia, the Pens have shown how losing your head may eventually lose a series.

I kept thinking of that lesson when I watched replays of Nicklas Backstrom cross-checking Rich Peverley in the face near the end of one of the most riveting hockey games in maybe three years at Verizon Center Monday night. If the match penalty Backstrom was hit with isn’t rescinded by the NHL lords of discipline the next two days, this early heirloom of an NHL Eastern Conference quarterfinal series would take a decided turn toward Boston.

Since the real hooligans are playing in Philadelphia Wednesday night, let’s hope the league office comes to its senses and makes this a fair fight. Because even with Backstrom, Washington found out in Game 3 how impossibly hard unseating the Bruins is going to be.

Defending Stanley Cup Champions 4, Not Quite Crestfallen Capitals 3.

It took the good part of three games but the offensive machines finally churned. After 1-0 and 2-1 overtime affairs in the first two games, the goals came. And came. For once in this tightly-contested defensive fracas of a series, it wasn’t just mano a mano in the net for 60-plus pulsating minutes until someone got lucky, made a mistake or fired home an overtime winner.

It was sublime playoff hockey until the end, when Boston’s banshee of a defenseman, 6-foot-9 Zdeno Chara, ricocheted a rifled puck off Roman Hamrlik’s stick in the final minute — past Braden Holtby for a Game 3 road victory the Bruins had to treasure at a stunned Verizon Center.

Unless Backstrom is gone for a game, there is no declarative trend or takeaway from simply the most riveting, hard-checking affair of Washington’s once-reeling season.

Oh, Holtby’s confidence had to be a little shaken after having given up just two goals in two games, just as the Caps’ rookie goalie’s more accomplished counterpart in net, the Bruins’ Tim Thomas, probably didn’t like the giant-sized Obama cardboard heads poking fun of his highly charged political decision to skip the team’s White House honoring ceremony earlier this year.

Maybe there was a lesson in mixing it up late with a chippy, physical team such as Boston when a penalty could be the difference in a series, when a suspension could ruin everything.

But mostly, in a series where neither the Bruins nor Caps has had a two-goal lead and both teams have spent much of their 200-plus minutes tied — coming into Game 3, they had been even for all but about 14 minutes in the first two games — the only real thought was this has all the makings of going to Game 7.

This is going to come across to the Rock the Red legions as a devastating loss, one in which the Capitals led twice and tied late in the third period on a beauty of a Brooks Laich goal.

Weaving his way from right to left, he sent home a perfect backhander that made it 3-3 with six minutes left. At that moment of bedlam, when you couldn’t hear the person next to you, it felt like this game was headed for overtime at the worst for Washington.

The Capitals put gobs of pressure on Thomas, who made a couple of point-blank saves to keep Boston safe. Washington beat the Bruins to the puck for much of the night.

The Caps scrapped and battled in the corners and, unlike the Penguins against the Flyers in a genuinely ugly series, they never got caught up in winning a fight as much as a hockey game — until the very end, when Backstrom retaliated for what looked like a trip on Alex Ovechkin.

If they found a way to go up 2-1, Boston would feel a mountain of pressure heading into Game 4 Thursday night at Verizon.

Instead, Game 4 becomes the Capitals proving ground. They don’t want to be that team on the cusp of going out in the first round in five games. No matter how contentious or close the series seemed, they still would be on the losing end of their third first-round series in five years with this group — the first with Dale Hunter, their coach for the time being.

For all the times he looked robotic this season, Hunter finally showed some emotion Monday night, shaking his head defiantly with 7 minutes left in the second period after Laich and Milan Lucic ended up in the penalty box. The Caps coach thought Lucic, having pushed Laich down, deserved to sit and his player be on the ice.

Alexander Semin turned and fired in the first period. Goal. Delirium. Alex Ovechkin glided down right wing in the second period.

Goal. Delirium. Welcome to the Russia House, Tim Thomas.

The Bruins would get the better of it at the end, though, unplugging the most electric night of the season in Washington.

It’s hard to say for sure, especially depending on what happens with Backstrom. But it would be no surprise if this doesn’t go to a Game 7 in Boston next Wednesday. In fact, after Monday night, it feels like that’s the least this series deserves.

For Mike Wise’s previous columns go to washingtonpost.com/wise.