Are you being obtuse on purpose to play the Devil's Advocate?
In 2012, Texas A&M played a SEC schedule. If you want to state the team was built while still in the Big 12, there is some logic to that, but their recruiting also picked up after they stated they were going to go to the SEC, so you can spin it that way as well. But, ultimately, they played Bama, LSU, and Florida that year.
And since you are in NYC I doubt you have (m)any A&M friends/acquaintances, but the vast majority of their fanbase that I know (I live in Texas) are extremely happy with their team and how they have performed in the SEC.
I'm fully aware they played an SEC schedule; that has nothing to do with my point.
Which is this: They did well their first SEC season with talent they'd acquired while in the Big 12. Unless you can provide a long list of stellar freshmen they picked up in the months between the announcement they'd be moving to the SEC and their first game as a member of that conference and demonstrate that it was those freshmen who elevated that team in 2012, then my point stands (if you have such a list, I'm eager to see it, but I won't be holding my breath).
So citing that season as evidence that moving to the SEC elevated their program doesn't fly. I would even question how much it helped them to a decent season in 2013.
Since then, they've finished all of their seasons but two unranked and with five or more losses.
Allow me to reiterate that: In the four seasons in which at least half of their recruits were brought in while they were members of the SEC and before the arrival of Jimbo Fisher (and his bagmen), they went 8-5 or worse every year and finished each of those years unranked (they went 8-5 and unranked Fisher's second season, too, so that five out of the past seven seasons).
It's Jimbo Fisher who has been the diffrence for A&M and it is he who has made those A&M fans content (I'm sure their fans are thrilled to be in the conference, but they're like Ole Miss, Miss State and other lesser SEC programs in that regard: They're perfectly happy to chant "S-E-C!" and pretend they're the cool kids).
If you want to suggest that Fisher wouldn't have taken the job if they weren't in the SEC, that's a reasonable stance. I don't buy it, but it's reasonable.
If Fisher taken the head coaching position at, say, Mizzou, I've no doubt he'd have seen similar results. However, he wasn't offered it and so we can see clearly how much of a difference being a member of the SEC has made for the Tigers. Like A&M, they had two good seasons soon after joining the conference (after one bad one), finishing 5th and 14th nationally those seasons.
In the six years since, they've suffered five or more losses every year but one (they went 8-4 in 2018) and they've finished unranked each of those seasons. So ... where's the impact of SEC membership for them?