Here's Wait 'Til Next Year's list of the top 75 prospects in baseball (via Primer). As we might expect, there aren't a lot of Pirates. Neil Walker is at #44 and Andrew McCutchen gets an honorable mention. WTNY author Bryan Smith is probably more excited about these guys than I am, though. I like Walker a lot, but I'll wait to get too excited until I see how he returns from his injury. Smith says:
Neil's ceiling is in the superstar category offensively... However, before I get too excited, I will have to see more than 20 walks in a season. Since there are very few other offensive problems to refine, I do think this is a problem that Walker can overcome in the next 2-3 seasons.
I think he probably can, too, but I question whether the Pirates will encourage Walker to improve his plate discipline.
On McCutchen:
I've seen some Pirate fans write that McCutchen is comparable to Marquis Grissom, but that's not right. Grissom has never walked more than 52 times in a season. Grissom's lifetime OBP is .318. McCutchen's upside is a much, much higher OBP than that. His plate discipline is already outstanding, and it'll stay that way if the Pirates don't try to ruin it.