the more my teams win in the regular season, the lower the chance they reach the WS (assuming the make the playoffs in the first place). the best regular season teams are constructed differently; more depth and B+ players across the board. the best playoff teams make good use of not only cookies like Milacki and Hill, but well-rested platoon guys. I do this a lot and it happens in real life too - look at Howie Kendrick last year for the Nats or what Giancarlo Stanton is doing for the Yanks right now. Is that really any different than stashing a 200 PA guy in AAA the whole season and getting max usage out of him in high leverage games?
one approach I've been doing more recently: downgrade the back end of your rotation to innings-eaters. a three headed monster rotation might mean you win 110, but I'd rather have two absolute studs and an innings eater, who win 100. if you're confident enough that your team will still perform, and get close to .500 performance from those guys, you can lean on the better players in the postseason. in fact, it's what the Yankees should have done with JA Happ last night - let him throw 10 garbage starts in the regular season then stash him on the bench for October!