In my twenty years of coaching high school football, there ISN'T a defense that by alignment and personnel usage that has an answer for everything that an offense does. You fill in the gaps by the scheme you employ. Even then, when you marry your scheme, what the offense is running and the individual play calls and you still don't have an answer sometimes.
When a team runs an overload either by formation, by personnel alignment or by play call, that is as much coach preparation and player identification as it is anything. One year, we had a tie breaker playoff in Southern Idaho on a Tuesday night to determine who got into the playoffs for the coming year. We faced a wing t team and in the two practices the only play they saw was a power/buck sweep overload and we repped it and repped it some more. We had the slide adjustment, a blitz into the pull, and when then the playoff happened (1st and 10 from the 20 going in) our kids froze in the moment. We couldn't make the adjustment and they got 7 players plus ball carrier to our 5 and TD. We had two small adjustments, in our 4-2, to make it free and easy for the kids to make the play, and it just didn't happen. Turns out those two small adjustments were too big for the kids in the moment, and those failures always fall on coaches.
As I said in the prior post, whether you are running a 40 front or 30 front with 5 line backers, the rules are essentially the same on how to beat power and overload. Coached against Tim Raccicot in his last years at Class in Frenchtown and we ran a 5-4 for much of the game. Didn't matter. Players are going to have to get cross face on the DL, feel double teams, and backers are going to have to scrape through a mountain of bodies to find the football that could be in the hands of two or three different personnel.
Having run power, overload and wing-t philosophies over the years, as well as spread zone schemes, you are taught to use what the defense is trying to do against them. Montana State used overload, and Montana's desire to remain a balanced in the middle of the field, to get more personnel to the POC. When Montana adjusted by running over fronts and overhang Safeties in the box, MSU stayed in the same formation and ran weak side zone, inside cut back zone, and got tons of first defenders to miss. Montana loves flow to the football and when teams like MSU who run inside and stretch zone as good as any team I've seen in recent years, you have to make a conscious choice. Flow really hard to the OS shoulder of the RB/QB or play straight up. Montana couldn't get flow into the gaps which is the calling card of the defense, and then they played straight up 30 and 40 techniques and got hammered some more.
MSU had a perfect play calling day, Montana didn't and on top of that our defense didn't execute. That goes on coaches obviously, but had Montana run out in a classic 4-3 it might have worked is the type of simiplistic and not realistic type of adjustment that coaches at any level are going to make if they know the odds of marrying personnel and scheme together for execution is pretty low. You coach to your strengths and in the MSU game you have to tip your hat to the playcalling and execution of MSU. They made Montana look slow and pedestrian on defense that day, and a 60 front likely wasn't going to change that.
Could have there been different adjustments? Absolutely, but just simply lining up in a 40 front wouldn't have been the silver bullet that some are asking for. Your personnel still has to be better at both levels, have to play the type of game that makes those adjustments worthwhile. Does your adjustment take away from a clear strength of the team? Does it change reads and assignments? Change eye level? What personnel do you have to remove or change? Just plopping another DE and playing an under front isn't going to make the offense coordinator go "Oh F@#$" and toss out the game plan. They incidentally have 8,500 hundred ways to block inside and stretch zone, including seeing 40 front. So you can strawman this by saying that no one runs a 3-3-5 anywhere at the FBS or Pro-Level else as your major argument, but aside from the interior 3-3 stack, what they do outside of it, with the other 5 guys is pretty damn standard at every level of football. Heck what they do with Patrick O'Connell as a flex/rush backer isn't weird, there are literal dozens of college programs at the highest levels that use it and several NFL teams. That is a 3-4 technique and has been around for 50 years at least.
