Bobick had more skill than Arreola, but his chin is simply too unreliable to pick him over anyone who hit harder than Hector Camacho.
Arreola, little doubt. He wasn't a great (Or even very good) fighter, but If you were chinny, regardless of your power, he went into a seek and destroy mode where he was willing and able, to take heavy incoming fire to connect his own big shots. He was actually very good doing so. Eric Molina, Travis Walker and Joey Abell were all super sized heavyweights with serious power. All three buzzed him early, but no one could take his equally heavy incoming power. Same thing happens here I believe. Grit, durability and a bit of power is enough to get it done vs Bobick.
Arreola takes Bobick out early, like maybe the 1st round. Bobick simply too slow a starter and Chris would be on him like a duck on a june bug.