It's a significantly flawed vessel, with a significantly flawed captain (Fisher). They caught a couple teams (Seattle and Arizona) at the right times, which happens, but they've never looked that good overall. The evidence has always been a .500 team at best assuming they got a more lucky than not. The distribution of wins won't look exactly the same every season, but the final results won't be that much different.

It's as simple as this. If you don't want to have to rely on luck, catching lightening in a bottle for a season, and you want a solid and sustainable winner, then Snisher has to go.