The over use of the bullpen isn't about individual players use, it's about the whole group as a unit.
If what another poster said above is true, that the Brewers have the 2nd most relief innings and THE least innings pitched by starters in MLB, then yes, the bullpen has been over used to the detriment of the team.
Another example of people cherry picking stats to benefit their point. No offense LouisEly, that isn't why I made this post.