Wallace was drafted in 2008, where everyone knows that he knocked the cover off the ball at Arizona State. As part of three different systems, he did about the same thing. Let's look:
Alright. From 2008-2010, Wallace's XBH/Hit% was an overall 32.6%, and his XBH/PA rate was 8.8%.
We're talking about a ridiculously small sample size in 2011, but so far, through 60PAs, Wallace has three extra-base hits - all doubles - for a rate of 5.5%. If you count his three doubles in 17 hits, that's a 17.6% rate, almost half his career minor-league rate, and well under his Triple-A rate in 2010.
It could be that he's just not seeing the pitches, and pitchers are throwing around him - Wallace's walk rate is 13.3% of his PAs, where it was 7.4% from 2008-2010. But if Wallace is going to inspire the confidence needed to get regular playing time again, he's going to have to flash the power that made him so coveted in the first place.