I stopped to think what Gibby did wrong and I can really only think of one:
-Pinch hitting Zeke instead of saving him as a runner. He still had Martin and Dominguez on the bench, and unless he wanted to burn Saunders he was going to lose Zeke by using him in the catcher's hitting spot. Pretty short sighted and, honestly, kind of terrible. May have been a huge factor if he could have run in the 8th for Saunders.
I don't mind him not bunting with Goins because... Goins sucks and can't bunt. When he did bunt in the 9th, he almost cost two outs. Dude is useless at the plate and his glove isn't a good enough justification for keeping him in the lineup. Barney is almost equal defensively, so might as well let him see if he can do something with the bat.
This loss is on the team, though, as most other losses are. The offense was at its nadir today. No way should Dyson have been able to wriggle out of that situation with a lead facing four of the league's scariest hitters and fewer than two outs.