The biggest problem is that the 4th and 5th starters would pitch in about 60 games, getting about 2 innings per game (really, less than that if they NEVER hit). when is the last time a guy pitched 120 innings in 60 games? Probably at least 20 years ago. OK, you could have more than 2 guys take those roles, so that they pitch less than 60 games, but then you need a bigger staff. Even with a 12 man staff, it's hard to have a bench that can supply 4 decent pinch hitters in a game. So basically, I don't think you could make it work outside of September. I do have an idea I think would work, if you could get the pitchers to buy into it. Basically, you'd have the best, sufficiently rested, pitcher pitch at all times, perhaps having a specialist or three to setup, close or face lefties. Your best pitcher would be always starting, because if he's sufficiently rested, he'd be the first guy to get the ball. You could go with a smaller staff, probably, and shuffle an extra guy onto the 25 if the staff is getting worked hard. The worst pitcher on the staff would get used in blowouts or during a period when other guys are getting worked over. With a smaller staff, you'd have an extra hitter to get more PH opportunities.