Considering the numbers I posted on chances to make the NFL by star rating - not the same thing but along the same lines - I'd say it's pretty standard.
"Only" about 50% of five-stars make the NFL. "Only" about 25% of four-stars make the NFL. There are a lot of "busts" to go around.
Just on a quick look, Callahan had two four-stars in the 2004 class - Grixby and Murtha. Both were contributors but neither were exactly game-changers. The 2005 class - where Callahan gets most of the love from, and not entirely undeserved - definitely had some studs. Suh and Lucky were studs; Dillard, Potter and Bowman were really good; but Beck, Picou and Brooks (the other four-stars) were busts. Plus several of the high-three-stars in that class were busts. The 2006 class was pretty mixed as well with Thenarse, Purify and Nicks being solid contributors but Andre Jones and Kenny Wilson not as much. Basically the same in 2007 with Paul, Zac Lee and Asante having nice careers but Jaivorio Burkes, Armando Murillo and William Yancy being forgettable.
Riley had much the same story - though they are obviously not final grades yet. In the 2016 class, POB is already gone, Dismuke and Jackson have been on the field but not been great and Raridon and Farniok working to get in the rotation. The 2017 class say Elijah Blades never make it to campus and KJJ barely better than that. Lindsey should be a stud and McQuitty will probably be good as well but Roberts and Gebbia are going to have to hurry to avoid getting lost in the shuffle.
So I don't think there would be much of a difference between our last three coaches. And likely not a huge difference between us and most other Power 5 schools.