A lot of factors go into deciding whether or not to sign an NHL player. General managers must determine how a player fits into the team's system, what role he may play in the locker room, if and how he may effect team chemistry, etc.
A definite factor GMs pay attention to is the player's ability—or lack thereof in some cases—to perform in the postseason.
Some players earn an NHL contract based solely on their ability to perform at a high level in the NHL playoffs. The opposite is true for players who can't perform in the postseason. If they can't elevate their game when it matters, all the regular-season goals really don't seem to matter.
The 2012 NHL free-agent class features several players who haven't performed well in this year's opening round, and their salaries might take a hit because of the lack of production.