Issue with the D... kinda long

So I went back and watched the Northwestern State game, and the Vandy game, and found a theme on 3rd down plays with regard to the offensive scheme and how LSU's defense reacted.

On third down both NWS and Vandy lined up, pretty frequently, with 3 WR's. 2 to the weak side, and one to the strong side, with a RB, and one TE. Knowing that LSU is bringing at least one LB, the RB would line up on the same side as the perceived blitzing LB. The offense snaps the ball running 2 slants, one from the slot receiver on the weak side and one from the lone receiver on the strong side. The outside is running a deep post to occupy one of the safety's.

It doesn't matter from which side the blitzing LB is coming, there is a slant being ran in the vacated spot where the LB would have been were he in coverage. So the QB just tosses the slant for 6 or 7 yards.

What should be happening is the MLB should be running to that vacated area, disrupting the play by taking away the QB's first read, allowing the time for the pressure to get home. It was a bit better in the Vandy game but they still missed that assignment too much.

Coincidentally, if you watch Bama's long TD passes, many come on the slant with the WR just beating the safety to the sideline resulting in long TD's with a ton of YAC.

Also LSU does the same thing offensively, just a little deeper WR routes.