I don't think that is necessarily what they are saying at all. Jennings making 3rd team doesn't automatically mean they think he would start for Bama. Just that more is known about Jennings than Bama's guys because they lost all 3 starters from last year. I looked at the rankings of the 3 guys they expect to start this year and all 3 were top 10 receiver prospects. I think Jennings would likely start there, but I don't think him making 3rd team was implying that. Just my opinion though.
Sure, we've already talked in this thread about the lists being skewed because the journalists who compiled them not knowing the depth charts of any of the teams. So starters, even at say Kentucky or Ole Miss, get a favorable bounce over the 2017 3rd stringers from other teams, like Bama.
But saying that the writers just don't know all the players who should be in consideration doesn't change what the 1st-2nd-3rd-4th team are about. They're about recognizing the best in the conference (or, as one poster pointed out, those who are expected to be the best in the coming year).
Which means that you absolutely can say,
in Athlon's mind, Jauan Jennings (as one example) is expected to perform better as a receiver in 2018 than most of the receivers at Bama now (Jerry Jeudy was 2nd team). Which means, theoretically, he'd start there.
Now, we know that's purely theoretical. Because JJ doeesn't know Bama's play book. The Bama coaches may not like his hair-on-fire attitude. They might be looking for a different kind or body build for their WR corps. Tons of details to consider in fitting a football player in any program.
But theoretically speaking, in a world where you can bring together all these players from across the SEC and make "teams" of them (1st team, 2nd team, etc.), JJ'd be ahead of all the Bama receivers not named Jeudy, according to Athlon.
