Brett Gardner seems to be struggling at the plate a little bit (.227/.261/.273, though he is 2-2 in steals). Melky's hitting just as bad at .250/.250/.250. I know it's early, but we all know how much the Yankees love instant gratification. So, who could the Yankees turn to outside the organization to fill a potential offensive black hole in CF?
Internally, the Yankees could switch to Nick "The Greatest Player in Yankee History" Swisher or Johnny Damon in center. While both of these moves would be an offensive upgrade over Gardner and Cabrera, they are defensive downgrades from Gardner. Swisher said he didn't like playing the position, and the numbers bear that out. Swisher is -9.5 UZR/150 in center for his career. However, his offense could make up for this, as it'd be a huge upgrade over Gardy. Swisher, and Damon for that matter, could probably manage CF without looking like complete morons, but I'd rather not have Swisher play a position he doesn't like or Damon play a position that he may not have the health to play anymore.
Externally, there's Milwaukee's Mike Cameron. Cameron was the subject of much debate in Yankee land over the offseason and there was a slight possibility that he was going to be the Yankees Opening Day CF. Now, the Yankees need another aging outfielder about as much as they need Joba in the bullpen, but Cameron is in the last year of his contract and would just be a one real rental. Cameron has a career line of .250/.340/.448/.778, good for a 106 OPS+. So, at the plate, Cameron has been just slightly above average. In the field, Cameron is a plus player, coming in at 5.2 UZR/150 in CF. Again, Mike has been above average for his career in the field. Yes he's old and we all want the Yankees to go with the young guys, but if Gardner doesn't develop over the next month or so, Mr. Cameron will look better and better.
Next, there's Texas's Marlon Byrd. He's five years younger than Cameron and is a pretty similar hitter. Byrd's got a career line of .272/.342/.409/.751. That's only a 98 OPS+, so very slightly below average. Byrd may not offer much in terms of power, but he's got a decent OBP and has a 2.6 UZR/150 in CF for his career (424 games). Byrd is also on a one year deal, having avoided arbitration with Texas. Byrd could be the better option over Cameron since he's younger and could be brought back to the team, since the Yankees could lose Johnny Damon, Xavier Nady, and Hideki Matsui.
Those are the two probable options for centerfield in my opinion. However, I'm not advocating for B-Cash to get on the horn and make a trade right away. I'm more than willing to give Brett Gardner around 300 at bats to see if he can turn this slow start around. Melky, though, I really have no faith in. He's had his chance and he is what he is: a below average player.