During my lifetime, Oklahoma has only been down for most of the 90s and maybe 3 years in the 80s. Perhaps they are due for a down period, and you never know with a new coach.
But I will say that Riley's "Coach Bro" attitude and cult of personality had created a lax, undisciplined atmosphere in the program. This is all coming out now not as speculation, but as fact. He also insisted on having the "Speed D" approach, which meant his S&C was focused on getting guys smaller and faster. It was succeeding at making them smaller only. That defensive mindset would've been great if it was the same Big 12 conference that it was when Art Briles was still coaching Baylor, but it isn't. You may have also noticed that the same approach didn't work so well recently with Patterson at TCU, whose defenses thrived on the "smaller and faster" thing for years. The conference has been trending away from its ridiculous offenses for a while now.
Every coaching hire brings risk, but it was apparent from early on that Venables was the guy. His former players at OU LOVE the guy, and I mean almost gay mancrushes. They say he is a maniac on the field and in practice and the nicest guy off the field, which is exactly what the program needs. He will bring a new focus to S&C and accountability both in the weight room and at practice. He's a great recruiter who will focus on the D. It's noteworthy that the entire D to this point seems to be completely on board. However, OU did just lose a huge commit to aTm yesterday-- one that could've transformed the D line instantly next year. Perhaps he'll flip again, but I doubt it because BV has reportedly gutted the old defensive staff.
5 years ago I would've said no way to Venables. Too much Stoops continuity and he didn't end his tenure at OU particularly well. But he has had vast, vast experience as an understudy to three HOF coaches and should bring a little of each. On paper, this is a great hire by OU. But again, you never know. I do, however, feel confident that he's the better coach than FULR for bringing OU into the SEC.
FULR, FWIW, is bringing much of the same staff and problems (including the S&C guy) with him to USC. Unless he has learned from his tenure at OU, which is entirely possible, he is likely to recruit great and put forth a product that decreases in quality incrementally every year. A lot of coaches at USC have done that.