Does an E8 put him to the top? That would instantly make him more accomplished than Nate Oats in the tourney.
I don't think one game changes things dramatically, would have to view everything as a whole. That's the same for Sweet 16 vs round 2 as well. I don't wanna get tied down to any particular tournament outcome being what cements Manning as a candidate and especially not as the ultimate selection. Completely hypothetically, if he goes 15-5 in the Big Ten and then loses in the 2nd round I don't think that's worse than going 10-10, somehow getting one of the final at large bids, and making a Sweet 16 run.
He'll have to have an excellent finish to this season to even have a shot. What defines an excellent finish has many permutations, but probably has to have a really strong showings in at least two of three of the Big Ten regular season, Big Ten Tournament, and NCAA Tournament.