The Curve's offense was led, of course, by Starling Marte. Robbie Grossman was the organization's minor league hitter of the year, but Marte had a case as well, and unlike Grossman, he has a ton of defensive value. He still has issues controlling the strike zone, with 100 strikeouts and 22 walks this year, but the closer he gets to the big leagues, the less of a concern that is. It would be nice if he had a 2012 season that put those concerns to rest, however.
The rest of the Curve's lineup wasn't as impressive. Jordy Mercer started the season in Altoona and played well, earning a promotion; Matt Curry got there by midseason and survived (which, given his lack of experience, is no small thing); Andrew Lambo seemed to recover there after flaming out badly at Class AAA. (Lambo posted a .464 OPS in a handful of games in June, then a .756 OPS in July, before posting a .906 OPS in August.)
Unfortunately, Tony Sanchez was horrible, hitting more like a future AAAA player than a top prospect. And several other guys who entered the season as semi-prospects weren't much better - Quincy Latimore, Jeremy Farrell, Brock Holt. The same players who racked up mostly-ineffectual at-bats for Altoona this year were the ones who led a 2010 Bradenton Marauders offense that looked like it could take over the world. Let's hope that 2011's world-beating Marauders offense doesn't meet a similar fate next year. (UPDATE: Vlad points out in the comments that this is assessment is less kind to Holt than it should have been. I'm not big on Holt as a prospect, but it's true that he probably does deserve a little better than to have his season lumped in with the likes of Latimore. I would be a little surprised if Holt didn't reach the majors. I wouldn't be shocked if Latimore didn't.)
The pitchers who soaked up the most innings were all interesting for one reason or another, although the only really dynamic prospect among them was Kyle McPherson, who continued to pitch well after making his way up from Bradenton. Jeff Locke spent the majority of his season at Altoona and made it all the way to the majors by the end of the year, but he looks like a back-end starter, due to his stuff.
Aaron Pribanic led the Curve in innings pitched. He's known for being a groundball pitcher but, unsurprisingly, he's gotten fewer and fewer grounders as he's moved up, and his strikeout rate is way too low to make him a legitimate prospect. Mike Colla pitched reasonably well, primarily as a starter, and earned a spot in the Arizona Fall League. He's eligible for the Rule 5 draft, but my guess is that it would take a dominant AFL performance to earn him a place on the roster.
Phil Irwin will be in the AFL also. He has posted consistently solid numbers in the past and continued to do so at Altoona. He doesn't have great stuff, and the falling strikeout rates (9.71 per nine innings at State College; 8.84 at West Virginia; 7.11 at Bradenton; 6.75 at Altoona) probably tell you most of what you need to know about his upside. But his control is very good, and he still gets a lot of ground balls. He'll probably reach the majors at some point, but I wouldn't bet on him to do much once he gets there.
The Curve's other main starter was Jared Hughes, who really took off once the Pirates put him in the Indianapolis bullpen. His stuff and performance were probably good enough to justify keeping him on the 40-man roster this winter. Aaron Thompson also started a handful of games for the Curve and got to the majors as well; there's really no reason to think he's any good at all, unfortunately, and I imagine the Pirates will slip him through waivers this winter. He didn't deserve the promotion to the big leagues in the first place, having not even mastered Class AA yet, and frankly, he pitched terribly in the majors despite somehow surviving in his only start.
Bryan Morris' stock took a dive earlier this year when the Pirates said he would be a reliever for the foreseeable future, but so far, he has done well in that role. His stats as a starter this year look like a line out of the career of Mike Felix (and let's take a sec here to let the people who still remember who Mike Felix was exchange knowing glances): 25.1 innings, 17 strikeouts, 16 walks. As a reliever, though, he struck out 47 and walked 17 in 52.2 innings. His velocity took a step forward as well.
The Pirates made Tim Alderson a reliever at the beginning of the year, and for a while, he suddenly looked like a prospect again, with 27 strikeouts against six walks in April and May. In June, though he struck out five batters and walked 10, and he didn't pitch well the rest of the year, either. His stuff is a disaster at this point. He's eligible for the Rule 5 draft, but unless some team has an incredibly ambitious pitching coach who thinks he can recover the stuff that had him making mincemeat of Class A+ batters as a 19-year-old, he won't be claimed.