They clenched. They choked. They made mistakes at terrible times. They had numerous clinching games and lost them all.
That doesn't mean they're too inexperienced to win or too unlucky. It just means they blew it. I'd believe you more if they got blown out of every series. That never happened.
Again, in 2006 they swept the Twins on the strength of their pitching then got swept by the Tigers. What do you make of that?