At this point of his career, is Tommy Hanson comparable to someone like Roy Halladay? Experts have made the comparisons and it remains to be seen if Hanson can fulfill some of the potential he has shown so far.
Considering a rookie's potential ceiling and whether he has the foundation of skills to develop into a better player past his rookie campaign is important - to predict future success.
Has a particular player gotten by because other he hasn't been exposed a second time - and in his rookie season, has already peaked?
Detroit Tigers rookie pitcher Rick Porcello doesn't have the punch-out stuff of a Tim Lincecum but Porcello was all of 20 years of age when he pitched in the Major Leagues, so there is potential for him to be better at 25, than at 20.
For starting pitchers, looking at their stuff is one key to predicting success - starting pitchers who enjoy success in the minors [maybe a pitcher who posts nice won-loss records] but don't throw hard at all don't have as much potential as pitchers who throw hard [or basically have pure 'stuff'].
Toronto Blue Jays rookie Ricky Romero has a solid rookie campaign, though it took a while for the first round pick to get to the Major Leagues.
On the other hand, guys who throw hard need command - otherwise they don't get anywhere.
St. Louis Cardinals outfielder Colby Rasmus' ability to make adjustments will dictate his potential ability to star in the Major Leagues.
For position players, the rookies who don't make contact and strike out a lot are not likely to have long-term success - however if a player is young enough and smart enough, the better ones make the adjustments.
I think this is where all the coaching and guidance a player has received may pay off - if a particular rookie has been told for his life just 'to play,' he might be at a disadvantage over another player who has received instruction as well as played organized baseball for much of his life.
Pittsburgh Pirates outfielder Andrew McCutchen provided a nice mix of athleticism and ability in his rookie season, giving Pirates fans a reason for optimism.