Of the three factors, nobody doubts defense. I don't think anyone doubts luck can play a role (round bat, round ball, all that). So really it's the newly age-old argument about controlling BABIP. The guys who take the mound say they can. That doesn't mean players aren't immune to observational bias and that's the final word. But I'm not going to be cavalier about dismissing their thoughts.
Jury's still out on Leake for me. For Arroyo, you have a lot of years that's harder to dismiss. He's a FB guy and a lot of those FB's are in the infield. That may explain lower than expected BABIP's.