Poor Mike, convinced the whole thing is his own fault even through there's no way he could have predicted that Stick would pull that shit. Maybe Stick could even tell him if he gets upset about it (I bet he's got the same temper Matt has, so I can imagine him getting really frustrated and angry at some point, shouting and yelling, maybe punching Stick.) that if he didn't think he could handle it, he shouldn't have agreed. Maybe he told him something really vague about this new level of training that with hindsight it's clear what he meant but at the time it didn't really mean anything.