Big 12 in SEC

I do not come here often, but has there been any discussion that maybe the SEC isn't as strong as most of you think? Two perennial Big 12 losers (1 championship between them both...last century) move to the SEC and instantly have success. I'm sure you guys have explanations/excuses for this. I am interested in learning what they are. I agree with all the Big 12 bashing I have seen here, but how is this consistent with the success of aTm and Mizzou in the SEC?