I don't think its as much about the unknown runner as it is the entire weight of situation. I think the end result was due to young pitcher, that hasn't really been tested all game, seeing multiple variables while trailing 2 runs:
You have fastest and smartest player on the field at the plate oddly showing bunt With runners on and no outs. You know he can reach base on laying one down...
You have no clue about the runner at second base drifting further and further off the bag, but he’s got a good lead. Maybe it’s an easy pick?
You have to not let this game get out if hand. The season depends on it.
That is a pressure packed situation with a few moving parts. Mix in a bad throw on an ill-advised pickoff attempt that subsequently moves the runners to second and third not to mention no relief in sight - Game over! A 19 year old kid isn't coming back from that.
Maybe I am making more out of that sequence than it actually was. I'm excited, of course ... But it seemed awfully scripted. Minus the error.
It Wouldn't surprise me if Mangum dialed that bunt up himself and it just happened to unfold in that fashion. Fuggit... we are one W away from the championship series.