That's the post-season for you, especially when there are multiple rounds.
In one of my earlier saves I had a team put up 116 wins, 125 wins, and another 116 wins in three consecutive seasons only to win the WS in that middle season, losing in the LDS both of the 116 win seasons to far inferior opponents.
It is one of the things I like about my WPK league at this stage of league development- if we can win the pennant we have a decent chance (at least about 50%) of getting championship rings.