For starters, let's just compare basic AA numbers from this year.
At first glance, the obvious winner here is Mat Gamel. He's having a disgustingly sick and nasty season so far, and his peripheral stats are decidedly drool-worthy. Without hesitation, Gamel gets the top spot for his overall plate discipline and contact rates, while LaPorta probably gets the early number 2 spot, and Davis gets the final, yet respectable number 3 spot due to an elevated K% and unpolished BB%.
However, the stats are only as good as the analysis, so let's dig deeper.
Looking at these numbers, there are 2 very important points to make. The first point is that Chris Davis is about 6 months younger than Gamel, and over a year younger than LaPorta, so we have to adjust our analysis to compensate for the age difference. The second point I want to make is that LaPorta's power numbers are significantly higher than Gamel or Davis, which seems a bit odd since Gamel actually has a much higher slugging percentage.
Based strictly on these power numbers, LaPorta gets the number 1 spot, while Davis and Gamel share the number 2 spot. If we take the age difference into consideration, Gamel drops to the number 3 position, and Davis easily takes the number 2 spot.
So, based off of a simple side-by-side comparison from 2008 stats, LaPorta and Gamel rank just ahead of Davis, but there's a problem with these stats and we need to recognize this problem if we're going to be accurate. In 2007, Chris Davis had 126 plate appearances at AA and posted an OPS of 1.067 as a 21 year old, with an ISOP of .391 due largely to a HR/PA rate of 1/10.5. To give you an idea of where Davis' 2007 stats fit in with LaPorta's and Gamel's 2008 stats, here's another quick comparison chart.
Even if we consider that 126 plate appearances is a bit short of an ideal sample size, the sheer power numbers Davis posted last year completely obliterate everything Gamel and Laporta have done this year, and the fact that he did it at an age 2 years younger makes any comparison seem like a joke. If we combine Davis' 2007 numbers with his 2008 stats, he makes a convincing case for the number 1 spot.
I think Davis' power numbers are impossible to ignore, even if he's not the best on-base guy, and his 2007 numbers put him above LaPorta. Unfortunately for us, that makes ranking these 3 hitters almost impossible, unless we make 2 separate lists to rank them according to contact and power.
Comparable Player: Lance Berkman
Early Projection: .285/.370/.540, 35 HR
Prime Projection: .315/.420/.625, 49 HR
What to watch for: While the Berkman comparison is legitimate, he also compares well to Travis Lee, who never really seemed to put it all together and retired with just 115 career home runs. I think LaPorta has a better chance of being a Berkman (or maybe Pat Burrell with more power) type hitter, but his strikeout rates could dictate how successful he is.
Comparable Player: Corey Hart, Chase Utley
Early Projection: .290/.340/.480, 24 HR
Prime Projection: .330/.400/.550, 34 HR
What to watch for: Gamel's power numbers have usually been low, with lots of doubles, mixed with a good OBP. His slugging percentage in 2008 seems abnormally high, and his top-end home run potential will probably sit in the mid-30's. His recent power surge could be a sign of a sustained improvement in the power department, but I think it's mostly a product of his age combined with a good surrounding cast at AA.
Comparable Player: David Ortiz, Mark Reynolds
Early Projection: .275/.355/.478, 38 HR
Prime Projection: .318/.420/.645, 55 HR
What to watch for: Davis has all the power necessary to be a successful major league player, and the Rangers seem eager to get him through their system. He has demonstrated that he can adjust to higher levels of play quickly, and his adjustments at the plate have helped him keep his K% steady at every level. His increasing LD% has helped keep his average up near .300 and there's no reason he can't do the same in the MLB.
If I had to go with an early success pick, I'd have to say LaPorta simply because he is older and more advanced than Gamel and Davis. However, Davis and Gamel both have serious potential, and I think that Davis will have the most impressive prime years. Gamel will be above average, but might take a few years to fully develop into an eye-opening player.