DeRuyter would be a vast improvement over Sirmon from a pure DC perspective... but Texas can do better than either.
DeRuyter is an excellent playcaller and runs a solid 3-4 D. He, along with Becton and Wilcox, turned the pile of steaming dogshit left by Sonny Dykes into a functional defense in 1 year and a pretty salty, if marginally talented defense in 2 years. Problem with TDR is that he doesn’t recruit for shit. He doesn’t like it, he’s not very good at it... it’s one of the reasons why Wilcox wanted to ease him out.
Sirmon is an outstanding LB coach... look at what he did with Evan Weaver and Jordan Kunasyk before that. The TDR system means your ILBs get tackles and those 2 LBs piled up 160-180 a year. But he has a shit rep as a play caller. Failed at Louisville and at Mississippi State. As I said previously, he and Wilcox are as tight as they come. They played together at Oregon, they coached together numerous times, their families are basically one extended unit...
Sirmon is a good recruiter but not a world beater. He recruits the Northwest for Cal and has pulled some really solid guys. But does Texas need to dip into Washington? Nope... there are only a couple guys a year they might want so can’t imagine it would be worth it. Sirmon transitioned to play calling this season but Cal only got 4 games due to COVID... small sample size and not terrible but nothing special...
Texas needs to move on from any thoughts on Sirmon. TDR would be a solid choice in the short term IMO but expect zero recruiting from him...