Other than catcher, SS is the most difficult defensive position. Pena is regarded as the best defensive shortstop in MLB by many experts, and he plays for one of the worst teams in MLB. He'll likely be a career utility player/defensive replacement, but as long as he stays with the Royals, he may continue to play everyday.
Barfield, on the other hand, is going to be a very good hitter. I had the opportunity to watch him play a lot with San Diego last year, and he was really impressive. He'll be much higher in this lineup before too long.
