He has only thrown a small number of them and there have been good but mixed results. It's just a crazy statement.
Just looking at the MSU game because there are the most examples, the first semi-deep sideline throw to Moore that went out at the 1, that's a TD if he puts it on more of a line. Moore was absolutely wide open for a TD but he put way too much air under it. That's usually good on a deep ball but it shows his inexperience because he didn't adjust to the situation.
Cook's drop was a very good throw, only a yard or two underthrown on a 45 yard throw so that's still a very good one. Cook dropped it because he couldn't keep his eyes on it as he chopped his last few steps to adjust to the slight underthrow. I am absolutely not saying that drop was Manning's fault because any FBS receiver still has to catch that. But having receivers that aren't great will come up later in this post. But for most receivers instead of a touchdown that becomes a long gain if they slow down well to secure the catch.
First half TD to Moore - This was a great throw because he was under pressure and about to take a hit, however this ball missed its target by 5 yards but Moore did an outstanding job adjusting to the throw. Moore was running a streak and when Manning released it he was running straight downfield 2-3 yards inside the numbers. He caught it on the run 2-3 yards outside the numbers. This one is a classic example of a play where the receiver determines what fans think of the QB's deep ball. Early in his career Xavier Worth absolutely would have missed this ball by 2 yards and everyone would have complained about freshman Ewers' bad deep ball because he threw it too far outside. This is a great play and a pretty good deep ball, but Ewers made several deep throws that were exactly the same that Worthy made look bad.
2nd TD to Moore was his best deep throw of the game. That was well placed, well timed, and pretty much perfect.
So he had one bad deep throw, one very good, one off target but great play because he was under pressure, and one perfect deep ball. He is very good but saying he's the best ever at Texas after this small sample size is silly.
And yes, VY was absolutely better at deep balls his junior year than Manning is right now. Manning very well could, I might say probably will, end up better before he leaves. But he's not right now, and failing to consider that VY's "deep threat" wide receiver was Billy Pittman and his 4.76 forty yard dash is a pretty big issue when it comes to this analysis. Manning is absolutely elite at intermediate balls in the 15-20 yard range especially in the middle of the field. He is a plus deep ball thrower. He is bad at timing routes to the flats (swing passes, bubble screens, etc.). That's all I'm saying. He is obviously an elite prospect who will be a great player here. All I laughed at was the prematurity of that declaration.