Perhaps in the late innings the effect of better bullpens should cancel the effect of better hitters negating some of the platoon advantage for hitters.

However, I respectfully submit that unless you have the luxury of 7 quality starters on your team you wouldn't really be able to PLATOON your pitchers like you PLATOON your hitters (And thats even assuming you could come up with a good mathematical scheme to platoon pitchers if you had 7 good ones).

Example #1- On one of my teams when Randy Johnson comes to town Erstad, Lofton, and Grieve go to the bench (1998 stats league) and are replaced by Bobby Bonilla, Roberto Kelly, and Melvin Nieves. This would tend to slightly increase the offense given up by Sir Randy who is killer on lefties but occasionally does get hit by righty hitters. The converse platoon advantage for pitching would mean that when you face a team with all righties you start all your righty starters and leave Johnson on the bench. I seriously doubt that anyone would do this.

Example #2- Some RHP are really good against righty hitting but are below average against LHP (Rolando Arrojo comes to mind). When I face a guy like this I might pull my part time players that hit left handed off the bench and give my right handed hitting starters a rest. Again... Unless you have 7 starting pitchers you really can't counteract this measure by 'platooning pitchers.'