Thanks for that link, lbarber. That is one of the most complete core workout outlines I have ever seen.
As for Pilates, I also have never tried it, but I have heard a lot about it. Generally, it is not meant to increase strength. It is for aerobic activity and increasing your range of motion. It might be helpful to your flexibility on the mound, but it wouldn't do much otherwise. If you look at the core workouts on the above site, those are centered around strengthening your core- which provides the power for pitching and hitting. I am a big time believer in this type of workout for athletes.
Longhorn, try to adapt some of those exercises into your routine- start with 5-6 exercises, 4 sets of 10 reps. I personally would try to integrate that with simple weightlifting exercises, like deadlifts, squats, dumbbell shoulder presses and others. 3-4 days a week of core workouts with 2-3 days a week of cardio and flexibility would be really good. I looked at your mechanics post and I really dont think pure strength will be an issue for you. You look like a naturally strong guy, you just need to refine the strength you have and add some more applicable power for your next season.
Good Luck This Offseason,