A generic reliever goes up there throws 1 2/3 innings and gives up a 2 run HR, that's a bad outing, sure. Letting the extenuating circumstances into the discussion, the kid showed some poise, and pitched well, got out of a nasty little jam in the 14th and nearly got out of the 15th as well.
Add that to the fact that he never should have been pitching in the first place as he'd just been called up that day and likely did some travelling to get to the game in time, well, it's just not that big a deal that he gave up a 2 run shot to one of the better RHH's in recent history.