Why is Bruce "I can't break a pane of glass with my fastball" Chen even on this team?

When he came in to pitch last night, I knew what was going to happen, and turned the TV off. Glad I missed it - here was his line:1 inning 5 hits 6 runs all earned 2 walks 1 strikeout 36 pitches 16 balls-20-strikes
He now has a sparkling ERA of 7.45 and hitters are batting .343 against him. Again I say - WTF is he taking up a roster spot?