They did OK with Schneider for the firs three years (1.97/.921, 2.26/.925, 2.15/.924) but your point about handing out big contracts is a valid one - Schneider got a 7 year, $42M deal, played well in Y1 and fell off a cliff. Part of that was injury - groin and then hip) and part of it was the Devils being woeful (although his three strong years with them got them zero playoff appearances).
Again, sometimes the contract you don't sign the player to is the better option.
They certainly showed how craptacular Mike Smith has been this year, with the Oilers giving up more goals than expected. That's 3 wins compared to an average NHL goaltender.
But really, Martin Jones has been horrible for the Sharks, and has been (by far) the worst starting goalie in the league this year. He's cost them 21 more goals than expected; so about 7 wins. Huge.