A couple thoughts:
1. platoon advantage is real, has been since the first baseball game was played. It's simply easier to hit pitches breaking toward you than breaking away. I also believe it's easier for humans vision to pick up the ball from opposite handed pitchers.
2. I think right handed hitters suffer less from the platoon disadvantage because they see way more RH pitching growing up than LH hitters see LH pitching. They get more practice. And the Darwin theory starts to eliminate right handed hitters whi can't hit RH pitching long before they progress to higher levels.
3. I often post "reverse splits are a mirage." It's sort of a joke, but mostly not. I'm very skeptical that true reverse splits are actually true, and not a statistical quirk that will correct itself over time.
As for Rocco:
I don't have a problem with using platoons. It's a simple and financially feasible way to squeeze some extra offense out of your roster. And as we can see, most LH bats never turn into good LH hitters against LH pitching. If Tony Oliva, Joe Mauer and Justin Morneau suffered against LHers, do we really need to give Wallner or Julien hundreds of ABs just to learn what we already knew?
My problem is PHing a RHed bat for a 1 AB platoon advantage in early or middle innings. That spot in the order is coming around again, maybe more than once. And there's a huge chance it will be against RHed pitching. You're going to be giving up the platoon advantage in at least one of those ABs. I'd rather let Julien face a lefty in the 5th and RH relievers from then on, over getting Farmer an AB against that lefty in the 5th, but then face those same RH relievers from then on. I truly believe teams have been intentionally putting Rocco in position to remove his best hitters.