I was a huge Doubting Thomas when it came to Pedroia. I watched him for a week in ST in 2007 and I was convinced that he'd never be much more than an average second baseman. After watching him day in and day out for two years, I acknowledge that I was completely wrong. This guy will find ways to adapt and perform at a vey high level no matter what adjustments the opposition makes. Maybe he doesn't hit 20 HRs or even 15 HRs in 2009, but I wouldn't doubt that he could hit .360 for the season with 50+ Doubles. The only thing that could keep that kid down would be an injury. I'm knocking on wood.
As for Youkilis, if he continued the offseason training that he started in 2008, I see no reason why he can't produce at the same levels as 2008. It's far from freakish that a player comes into his own at age 28-29. Yaz was a 15 HR 80 RBI guy until he was 28. He started an off season strength and conditioning program, and won the Triple Crown at age 28. He also hit 40 HRs and drove in more than 100 runs for 3 of the next 4 years. Barring injury, (knocking on wood), there is no reason Youk cannot maintain his 2008 performance level.