Here’s an example.

During the third period of Game 1, Nick Bonino takes a pass from Carl Hagelin in the slot and gets one past Braden Holtby. The location of this shot is one of the most advantageous for a skater –converting at roughly 18 percent of the time during even strength — but Holtby has a clear line of sight and extra help from defenseman Nate Schmidt in front. However, the puck takes a weird hop off Schmidt’s stick to become Pittsburgh’s third goal of the night. The Capitals would go on to win this game, but it should not have needed overtime to decide it.

In Game 2, Evgeni Malkin sends a saucer into the slot where it deflects off Eric Fehr’s stick. Holtby allows shots from this angle to convert only 16 percent of the time, but one fluky bounce makes this one the game-winning goal with less than five minutes to play in regulation.

Trevor Daley’s shot in the first period of Game 3 starts off just inside the blue line and carries a 3.6 percent chance at lighting the lamp until Patric Hornqvist deflects it past Holtby, giving the Penguins an early 1-0 lead.

A minute later a Matt Cullen pass would go off Tom Kuhnhackl’s back and in the net, putting the Penguins up 2-0 en route to a 3-2 final score.

Daley’s goal in Game 4 originates just inside the scoring chance area, giving it, at best, an 8 percent probability of success — and that’s not factoring in Capitals defenseman Karl Alzner is in good position to block the shot. Only it caroms off Alzner’s skate, eventually finding its way past Holtby to tie the score in the first period.

I’d agree with you if you said that good teams make their own luck, but Pittsburgh has been outshot 144 to 136 in the series, with high-danger scoring chances — those that originate in the slot or crease — also in Washington’s favor (51 to 42). According to Emmanuel Perry, after adjusting for shot location and volume, the Capitals should be outscoring the Penguins 12 to 11, and be tied in the series after four games. Instead, it’s the Penguins who have the lead on the scoreboard thanks in part to potting goals that have low probabilities of success in the first place.