Braelon Allen doesn't think it's silly.
I mean, he's also talking about nine-man boxes, which you're basically only going to see out of a couple formations/personnel groupings. Seems like he's speaking in vibes more than actual numbers, and it's true, UW being RPO heavy and high-tempo will very likely be pretty damn fun.
But box math is pretty simple. The defense controls one, occasionally two when it comes to the numbers (you have 1-high safety, making you plus-1 in the box, or 2-high, which is even. Sometimes you go 0-high, but that's usually about where you are on the field). The offense can control up to 5, though usually only four.
So if I play a fullback and tight end, that means I have two DBs split out with my two WRs. And if I have Braelon Allen, my opponent very likely is going 1-high. Thus, just by running Wisconsin's standard personnel and being good at running that ball, ta da, 8-man box.