Do you think he is a good bet to be a major league starter?
Go back and look at some of the rankings for the last decade. There are tons of A and B+ prospects who never pan out. Sure, they don't wash out as often as C prospects (almost all of whom wash out), but they still wash out at high rate. I'd guess that only half of the top 10 prospects in all of baseball for any given year ever amount to anything. A 50% washout rate beats the heck out of a 95% washout rate, but it's still a darn high hurdle for a prospect to clear.