Despite being age 24 last season, it is safe to say Upton had a down year. Most notibly, his OPS dipped from .896 to .785, mainly because his doubles dipped from 39 to 24 and HRs dropped from 31 to 17. In fact, the only catagory Upton had a higher total in 2012 than in 2011 was runs scored, as he had 107 in 2012, having 105 in 2011.
Fowler, on the other hand, played in a career high 143 games last season. Colorado ran him out there almost every day, in spit of missing some time due to injury. From an OPS perspective, Fowler had a better season, finishing at .863. But lets understand, though, Fowler is a different type of player. Fowler plays CF, and uses his speed as his main part of his game. The 68 walks he drew certainly helped his OBP, and he laced 11 triples, the forth straight season he had double figures in three baggers.
Before I dismiss this comparison completely, Fowler has an upside when it comes to power. The Rockies used him on several occasions in the number 3 spot of their batting order. In addition, his 2B (18), HR (13) and RBI (53) totals should all be expected to improve next season.
The problem I have with this comparison is how easy it has been to claim that Upton is now a .280, 17, 67 hitter. He is not. Upton should clearly bounce back and hit closer to his .289, 31, 88 season of 2011. He may even surpass those numbers in 2013. Fowler may to off at 20 HRs, and if he bats 3rd, could drive in 70 runs. You can't even make the case Fowler is a base stealer, being he only stole 12 bases in 2012. So, this long answer turns out to be an easy answer to a potentially confusing question. Upton> Fowler, even at Upton's worst, which was his 2012 season.
The Rockies have some depth in their OF, especially with Todd Helton expecting to be the everyday 1B again in 2013. Fowler, Carlos Gonzalez and Michael Cuddyer are joined by the emerging Tyler Colvin as the Rockies have 4 OF to fill 3 spots. The Rockies definately want some pitching back in a trade, but would also like to upgrade at 2B and 3B. The Rockies would be silly if they did not explore moving either Fowler or Cuddyer, though Cuddyer's contract may scare some teams away. Teams that have interest in trading for Fowler probably look at him as a speedier, poor mans Upton, who can score 100 runs, get 20 2B, 12 3B, 18 HR and maybe drive in 70 runs. Many teams would sign up for that for their CF. I'm sure the Mets, Phillies, White Sox, Twins and Rays would all want Fowler on their team. In addition, if Texas, San Francisco and Boston (if Jacoby Ellsbury gets traded, which is unlikely) lose their CFs, Fowler will become a much sought after target.
Upton will probably not be traded. Lets be honest, Arizona would still ask for a ton back in a trade; a SS, starting pitcher and probably another MLB ready piece to even start a discussion. The D'Backs are banking on the same thing trading teams are, that he will rebound in 2013 and probably surpass his 2011 numbers on a yearly basis. His value to the D'Backs is much higher than his value to most other teams, so that middle trade grounds is unlikely to be met. Thats why, I think Upton will stay in Arizona at least through this upcoming season. The same cannot be said, however, for Fowler.