PITTSBURGH — Sidney Crosby, diagnosed with a concussion earlier in the series, slammed head-first into the boards after becoming tangled up with Washington Capitals goalie Braden Holtby and defenseman John Carlson late in the first period of Game 6.

Social media immediately lit up about why the league’s concussion spotters didn’t pull the Pittsburgh Penguins star off the ice, given his history and the severity of the blow.

“When you go in like that it kind of knocked the wind out of me,” Crosby said after a 5-2 loss to the Capitals. “Kind of a fluky fall, but not one you want to take too often.”

When Penguins coach Mike Sullivan was asked whether Crosby was checked for a concussion, he answered, “No.”

Spotters have specific criteria they must follow to remove a player from a game. It includes: if a spotter observes or knows that a player is exhibiting any symptoms associated with concussions such as nausea, headaches, sensitivity to light. Other criteria include lying motionless on the ice, a blank look, a lack of coordination, or being slow to get up.

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Crosby, whose 19:57 playing time led all Pittsburgh forwards in Game 6, was slow to get up after the tumble into the back boards with just over two minutes remaining in the first period.

In Game 3, Crosby was cross-checked in the face by Washington defenseman Matt Niskanen. He was held out Game 4 and completed the concussion protocol before being allowed to play in Game 5.

Follow Kevin Allen on Twitter @ByKevinAllen.