Jonas Hiller had spent his NHL career being, at worst, an average starter. He even experienced a resurgence when the Anaheim Ducks decided to move on from him and the Calgary Flames picked him up: playing 52 games for the Flames last season, he posted a .918 SV% (.927 ES SV%, 11th amongst goalies with at least 40 games played), and was a huge part of their stabilization en route to a surprise season.
So his sudden cliff-diving this season was surprising. And a pretty big part of the reason why the Flames' year went the way it did.