Wasn't he drafted out of high school? 4 years seems about right to me.
Regardless of when you are drafted, you should make steady progress. A high pick, regardless of age, should see some time in AA by the end of his 2nd year of pro ball, and first rounders are usually expected to be decent enough to qualify for a September call-up after 2 years and not later than 3 years. Anyone who treads water and makes no progress at low levels for 3 years is often released. If he had been a low pick, which is what it turns out he should have been, he would have probably been released. But, since there was $1.2 million tied up in him, he was given a 2nd and 3rd chance.
All that said, I rate him a bit better than most scouts. I think he'll need to spend 2010 in the minors, but may make a bottom rotation starter in 2011. He'll still only be 24, and more like a mediocre college pitcher. It will take him a couple more years, and he'll be 26 or 27 when he starts pitching his best and, I believe, may make a mid-rotation starter (though virtually all scouts disagree, topping him out as a low rotation guy).