re: Why can't the SEC produce great QBs every year?

I agree with you that it's not so much true anymore over there as it was 5-7 years ago due to new coaches implementing spread offenses but among the top teams in that league it most certainly is.

A&M, Ole Miss, Kentucky, Vandy, Florida, State, Mizzou, South Carolina, Auburn (running QB) and Tennessee (dual threat QB) offenses are built around the QB. It's no surprise that these are the teams that have the most productive college QBs in that league.

Alabama, LSU, Georgia, and Arkansas all design their offenses around the RB position. It's no surprise that these teams produce the most productive college RBs in that league. A lion's share of the DL/LB talent produced in that league is produced by Alabama, LSU, and Florida when they have their act together, not the entire league.