I'm not sure Gibbons can really be held responsible for the starting rotation being a dumpster fire. He doesn't build the roster.
Yeah, the rotation has had a horrendous year, but watching this team as much as I have this season, there are things Gibbons and his team did have control over:
1) They lack the basic fundamentals in batting and in the field. So many mistakes repeated and repeated that they could have worked out with some coaching.
2) People have praised him for use of the bullpen, but he never lets his starters, when they are having a good outing, go any further than six or seven innings. He's either married to a pitch count or doesn't have any trust in them. And when he did have one of the best bullpens, he relied completed on Cecil and Delabar, the latter ending up on the DL from overuse.
3) This team has been under .500 for the majority of the season, yet when this team hits a home-run, they do the stupid V salute or jump around like idiots. They win one game in ten and they are doing stupid jump celebrations in the outfield. It's so bush league for a team that has been absolutely dreadful.
The only other theory I subscribe besides AA and Gibbons complete incompetence is that this clubhouse is being run by Bautista and has stopped the staff or the new players from having any kind of influence to make this team better or they have been sucked into this black hole as well. Why do I blame Bautista? He's been constantly consulted by ownership or the front office over the manager or anyone else. He's got no fear of goofing off in the dugout in Houston when they are getting bitchslapped by the worst team in baseball. If you aren't going to fire AA and Gibbons, trade Bautista and pick up some useful pieces to shore up the other holes. Let him be someone else's problem.