Chris Ash was a very highly regarded DC at Wisconsin, OSU, and Texas. He was a terrible HC at Rutgers, but Rutgers sucks. Al Golden did have a better HC track record at Temple and Miami. I like the Ash hire, and think he has a similar record as DC to Knowles, who I think would have been one of the only others higher on the list.
My big concern is the interior line, but I am less concerned than I normally would be because they got a lot of reps last year.
No knock on Golden, but I've always felt Golden ran his own version of Freeman's defense. Marcus Freeman was a big pickup as DC when we got him against some pretty stiff competition, including Ohio State and LSU. Golden was a perfect hire as a steady hand at D while he learned the ropes as HC. Ash continues this trend.