I think you're right. Chambers could have stopped Peter just by being more active and throwing the right hand more often. Peter was ready to go from exhaustion alone if Chambers had kept up the pressure. Arreola is a much heavier puncher than Chambers, and commits to his punches more. Peter would likely fall in the late rounds due to punishment or exhaustion.
Sam Peter is not up to the task anymore....he doesn't have the motivation to win IMO. It would be a good slugfest though and I'd tune in for sure. Arreola makes him stay sitting 7-9 rounds in.
sam peter is motivated to KO ice cream vendors who dont give him what he wants, outside of that i dont seem him doing much,