This begs the question of will this be one of the more brilliant signings of the winter or just another space filler. At first brush, he strikes me as a one-year wonder ('08) that has come and gone. He's started more than 10 games in 3 seasons. He's had one average year ('07) one good year ('08) and one terrible year ('09).
According to his baseball-reference page his career has been similar to luminaries such as Joaquin Benoit, Willie Banks and Marvin Freeman.
For a better answer, it's time to consult Ron Shandler's baseball forecaster for further insight. He ain't repeating '08 but I see him as an inning-eater. Bad luck can be blamed for some of his struggles as his opposing H% was 35 (he was in the 27%-29% range the previous three years). This inflated his WHIP (although his decreased strike percentage helped out), his hr/fb and flyball percentages stayed within his historical norms.
Verdict: If he makes the rotation his ceiling would be 10 wins/4.5 era. He works as a stop-gap/innings-eater/likely to do better than your typical AAA player but not someone who's getting a long term deal or on very many fantasy teams anytime soon.