The highlights I saw included a lot of 3 LB sets (per the roster), though they're not always lining up in traditional LB spacing they're probably being used as hybrid safeties. Kind of like a faux Tampa 2. The coverages are just getting worked by good offenses.
4-2-5 will almost always result in (at most) 7 in the back..... 3-3-5 can result in 8 in the back or it can have a normal 6 or 7 man box depending on what the offense comes out in. It's just a better pass defense. I'm not saying the Chicago Bears should adopt it or anything.... just that in college with the commonality of spread offenses, being better against the pass will give you a better shot in more of your games. What's ironic is that I also think the 3-3-5 leads to more penetration in the backfield because it's always coming from a different direction. When we had guys like Jaxon Player, Trevis Gipson, and Devin Lamp we were causing real problems.
In any case, we've got to get better cover corners if we want to compete with state schools again.