It's a combination of things that varies from game to game. Sometimes you feel like they don't get their legs under them until the third period. Sometimes it feels like they just outlast the other team. Other times it just seems to be luck - like Saturday for example. Scrivens robbed a couple guys in the first two periods. It could have easily been tied after 2. The Flames stayed on the pedal and the chances started to go in in the 3rd.
tl;dr - you can't pinpoint it to one thing, in my opinion.
__________________
|