SDSU has been great on defense for a singular reason: Rocky Long.
He was the head coach at New Mexico for 11 seasons (1998-2008) ... only had one 8 win season and one 9 win season there. Tough place to win, I guess. Then Brady Hoke went to SDSU in 2009 and hired Rocky as his DC, which he was for 2009-2010. Hoke quickly got SDSU to 9 wins in 2010, and then skipped town to Michigan. But he couldn't convince Rocky to come with him to Ann Arbor. And we know what happened after that.
Meanwhile Rocky stayed to become the HC at SDSU ... but he also kept the DC duties for himself. This is his 8th season at SDSU, and they've won 8 or more games every year except one 7 win season. He's had two 11 win seasons, a 10 win, and a 9 win. They're 7-2 this year, facing stiff competition from Fresno since Tedford arrived.
Only in 2017 did Rocky finally give up DC duties. Danny Gonzales had it for one year in 2017, and was immediately scooped up by Arizona St. Now Zach Arnett is the DC for the first time in his career. *IF* he gets scooped up by a P5, my bet is that he would prefer to stay in the far west, so a PAC program or maybe a Big 12 like Texas Tech or something along those lines. Wild guess.
All well and good .... but none of these people have anything to do with Fleck. I doubt Fleck has ever met any of them.
I'm not at all saying it's a bad thing to reach out of your known circle/coaching tree. Can be a good thing actually. I just don't get the attachment to this particular 1st year DC. There are plenty of others, which been mentioned in the thread as well (Fresno, N ILL, Temple, etc).