Chen IS going to dominate if he continues getting everything just off the plate. It's tough to hit even mediocrity if you can't get them up into the zone and if Chen knows that he's going to get everything just off he's going to continue going there.
That's what happened early in his last start in Atlanta. He got everything just off and it was looking like a disastrous game early because no one could hit due to that. When he had to get in the zone, he was getting hit. When he wasn't, he was dominating.