I'm swallowing my pride and admitting I was wrong here—Pagan is actually a pretty good player. 2 years ago in limited duty (376 plate appearances) with the Mets, Pagan posted a .306/.350/.487 line and a UZR score of 7.0, making him a 3.0 WAR player.
At the time I was skeptical, considering Pagan's lack of production at the major league level prior to this, and his slugging percentage seemed a bit inflated. While my suspicions about the slugging percentage were justified (down to .425 in 2010) he maintained a good batting average and OBP, which coupled with his speed (37 steals) and above average defense (15.1 UZR in '10) made him worth almost 5 extra wins to the Mets over a replacement level player at the same position.
If we strictly look at WAR (which is pretty all-encompassing, hence I use it so much) Pagan has been the eleventh most valuable outfielder over the last 2 seasons; more valuable than such players as Justin Upton, Nick Swisher and J.D. Drew.
While time will tell whether or not his value can be sustained (his success is built on some tenuous things that can disappear quickly, like speed) I think it's safe to say Pagan is one of the more underrated players in the game right now.
God, that's painful to admit.