Solid move here. Cowgill had two great years in the minors in 2010 and 2011. At the very least, he's a fourth outfielder option or off the bench..at the best, he lives up to his potential and becomes a decent to good baseball player, with speed and doubles to back up his average.
Marte, in the minors since 2008, was going no where. His numbers were seemingly identical to one another year after year, and he's blocked at first and third. The fact that anything could be gotten for him is positive.
So overall, a small move but a smart and decent one adding an outfielder when we need some.