I dont think its that easy to improve with the quality of players on the team guys like amaya and the hist of bad outfielders had been getting significant playing time. True they are near last place but last year they were in last place. By nearly all metrics they have improved. And with the quality or lack thereof of players on the team that pretty good.
Unless you think that Getz has gone out and gotten better players, improving the hitting stats of a bunch of bad players is a pretty impressive feat.