There is some quick fix stuff. Fire Enos and bring in a spread OC. I like Bill Bedenbaugh but I get that fans want someone who as called plays. So Diaz can do what Coach Orgeron did and hire an OC who was open to having a young buck help him innovate. Hence he got Ensminger as the primary OC and brought in Joe Brady to add spread concepts. Diaz could do the same with his old buddy Larry Fedora and hire Bill Bedenbaugh as the OL coach/co-OC. Fix two problems off the bat. I don't want Fedora alone- we'd just have the same problems again. Bedenbaugh would be the "OC in waiting" since Fedora would likely bounce to a HC gig in a couple years (yes, it's an upgrade for Bedenbaugh as he will NEVER call plays with Riley at Oklahoma). Yes, Diaz could bring someone in to help Enos but Enos doesn't think he needs help.
2nd, Coach Orgeron didn't hire some nobody backwoods hillbilly as his DC. His DC, Aranda, makes nearly as much as he does because he wanted the best in the business. He can worry about the big picture than focus on taking back the defense. Embarrassing that Diaz had to step in at one point this season to help his DC. Diaz needs to put his pride aside and get a DC who is better at defense than him.