It's easy to lose perspective during a playoff race. The only goal is to have the best possible chance of winning the World Series, which usually means trying to win your division and trying to win home field advantage. If a team falls short of that, their season can be viewed as a bit of a disappointment, no matter how good they are.
Take the Pirates as a huge example. After last night's win against the Rockies, they sit 90-60. That's 30 games above .500 with just 12 games remaining. It's a .600 winning percentage, which is good for second best in baseball.