I have been wondering the same thing. I bought low on him in my dynasty league but he is currently riding the pine in favor of troy glaus until he shows me he can hit.
His BABIP is showing he is getting unlucky with his batting avg right now. He has a .249 BABIP, compared to .323 and .317 the past 2 years which shows there could be a light at the end of the tunnel. However, he had a .269 BABIP through 89 games in '07, so his cold streak could continue. His bb/k ratio is down to .34, compared to last year's .53 which is looking like an outlier. His FB% is way up from 36.8% last yr to 42.9% this year. I think those three ratios/stats mean he could be just trying to hit the ball as hard as he can right now, and as a result he is the culprit of a lot of fly-outs that aren't leaving the stadium or finding the gaps. Also, his 19% HR/FB ratio last year is looking like an outlier.
In the preseason, many sites that look at these deeper stats such as razzball and baseball forecaster stated that this guy's breakout year was fully supported by his deep stats and that he shouldn't slip into bust territory at all this year. So far, they have been dead wrong. We still have about 2/3 of the season left to play so he has plenty of time to turn it around, but this guy is young and could put up monster seasons with a chance at continued growth in HR. He has 8 HR on the year so it is not impossible for him to reach his preseason predictions, but here's hoping he starts mashing soon.