oh fundamentals my ass. So far the only fundamentals problem has been Robles. And I'm not worried about him, he'll be fine. And don't tell me about Strasburg and the play at third. Strasburg should never have been in the position to have to field a throw and tag out a runner at third. Simply put, you should never be in the shift with a runner on base. ANY base. But that's a strategy problem, not a fundamentals problem.
I'm not willing to go so far as to say you should never shift with any runner anywhere, but something's wrong if a single to left-center results in the pitcher covering third. There are two bases to cover on that play, and whichever infielder is closest to third has to be able to get there.
If he can't, then he's either an idiot or the shift is too extreme. In this case, it's largely on Rendon: it's tough to act against instinct, but in that situation you just can't dive on a ball to your left unless you're 100% sure you can get it. It's like going first to third with two outs, funnily enough. Of course, if you're a manager who has to deal with players who make mental mistakes, you must adjust to put them in positions in which they can't make those mental mistakes.