Constantly starting the wrong guys

[Niffoc4]

Like its been said size and rules of the league make a big difference in whether you should keep bench hitters.
I play matchups with players who have shown a tendency. For example, Hank Blalock and Nate McLouth tend to find themselves on my bench when they are facing lefties. Clint Barmes only plays in Coors and on rare occasions against lefties on the road.
On the playing the 'better players' line, if someone has a thousand ABs against lefties and has shown that they can't really hit them, then platooning them when someone else has a better matchup maximizes your results. Sure, sometimes Hank Blalock hits a homer against a lefty... its happened 29 times (in 922 ABs). But I'd rather throw someone else out there on those days.