Sure, 6 OL sounds nice. But you run the risk of roster imbalance when you start taking more guys at a position than you can even play in a game. This isn't WR where you may line up 2-5 guys on any given play. It's pretty much 5 guys, period. It also isn't a position, where once the guys are in the game, they really sub out. Then add in the problems it can cause next year (and subsequent years) with recruiting. How many top OL guys are going to be interested in ND next year knowing they just took 6. And it's not like there's a huge number crunch at the OL position to mitigate why the staff should load up on them this year. Taking 4, 5 max OL is fine for this coming year.