It's a combination of many things IMO. The best defensive coach I can remember iu having the last 15 years would probably be the guy during Cameron's last season, James Bell. Other than that, I simply don't remember a quality defensive coach. However, I can remember multiple coaches on the other side of the ball that were competent coaches.
The other issue is lack of speed on defense. Yesterday I was forced to run between my bedroom and living room, trying to watch IU and UL on two separate televisions. It is stunning how little overall speed IU possesses defensively, especially in the front seven. I understand the best three players were out, Ralph Green, Tegray Scales and Darius Latham, but it speaks to our lack of division one depth and speed.
I thought Wilson was upgrading our recruiting, these guys were mauled at the LOS yesterday by an FCS team. This is why it's so disappointing. I read in the Courier-Journal that Indiana actually gave up 400 yards in the 1st half alone!! The coaching is not good if that's true.