Did you really just compare Doumit and Kubel to Drew Butera?
Flawed players are just that, flawed. If they weren't, they'd be "superstars". Guys like Doumit and Kubel are vital to the success of an organization. You litter a lineup with those guys and throw in a Justin Morneau and Joe Mauer at the core of the team and you have a playoff contender. Complementary players are important, even if they have flaws. The key is that the player does something significant to help the team win. Kubel and Doumit do that with the bat. Butera... doesn't.
They are comparable in that they are pretty one dimensional players. Kubel wasn't very good at all in the field but could hit, same for Doumit. Butera is a good defensive catcher but coulding hit the ball to save his life. Butera is a more extreme example but the basic comparison is true.