Look at his stats. He has never topped 7.33 yards per attempt in a season. His career average is 6.99. On top of that, he throws far too many INTs. 93 passing TDs in his career. 62 INTs. For the sake of comparison, Rodgers has thrown 220 TDs against 55 INTs. Luck already has 80 TDs against just 38 INTs. I'm not going to go through every player's history and dig up the stats, but I'll venture to guess that virtually no QBs in the past 10-15 years who were as mediocre as Dalton after the first 60 games of their NFL career went on to become elite QBs. He's a very bizarre choice for the list because there's almost no mystery about him. We've seen enough of him to know what he is, and what he is isn't an elite QB. It's like saying Torrey Smith is the next great WR. If that were his destiny, we'd know it by now.
First four years
Peyton Manning 111 TDs, 80 INTs, YPA 7.4, 32-32 record, 0-2 postseason
Andy Dalton 93 TDs, 62 INTs, YPA 7.0, 37-27-1 record, 0-3 postseason
This is actually a surprisingly fair comparison, since Dalton had AJ Green, and Manning had Marvin Harrison. Dalton had Gio Bernard in there, I guess, but that doesn't compare favorably to Manning, who either had Marshall Faulk or Edgerrin James every year. Dalton had Gresham and then Eifert, Manning had Pollard. Manning's YPA was a little better, and it was a tougher passing era, but in the year that Marvin Harrison missed time, his YPA was only 6.5.
Tom Brady 97 TDs, 52 INTs, YPA 6.7, 48-14 record, 9-0 postseason
Andy Dalton 93 TDs, 62 INTs, YPA 7.0, 37-27-1 record, 0-3 postseason
Brady had a better TD:INT ratio, and obviously won a lot more games in the regular and postseason, but his YPA wasn't great, and people were still calling him a low ceiling, caretaker quarterback. One obvious difference is that Brady didn't have the quality at receiver that Dalton and Manning had, but there was no real indication of the elite fantasy numbers he'd go on to put up later in his career.
Drew Brees 99 TDs, 53 INTs, YPA 6.8, 30-28 record, 0-1 postseason
Andy Dalton 93 TDs, 62 INTs, YPA 7.0, 37-27-1 record, 0-3 postseason
Again, Brees had a slightly better TD:INT ratio, but his YPA wasn't as good as Dalton's, and he wasn't just considered a weak QB, they drafted a quarterback and outright released him, and QB-needy Miami even passed on him for Daunte Culpepper. He played all of his first four years with Tomlinson, and two of them with Antonio Gates, including Gates' breakout pro bowl season.
It's easy to say that his numbers should be better, but when you compare him to three of the top QBs in NFL history - currently first, fourth and fifth in all time touchdowns - he doesn't look that far off. So let's compare him to Tannehill, who is a year younger:
Ryan Tannehill 56 TDs, 39 INTs, YPA 6.7, 22-22 record, 0 postseason games
Andy Dalton 93 TDs, 62 INTs, YPA 7.0, 37-27-1 record, 0-3 postseason
So yeah, Dalton's numbers aren't on the same gaudy path as Luck and Russell Wilson and Cam Newton, but those guys have already emerged as elite and you're not going to be able to buy them cheaply. Dalton's flashed one great fantasy season (which was also an 11-5 regular season that had people buzzing until their first round playoff exit). But it was also the first season where he had legitimate alternatives to AJ Green, and while his numbers have regressed somewhat this year, I think his ability to get the ball to secondary receivers has improved because he's been forced to do it more often instead of forcing it to AJ whenever he got in trouble. And that will make him a better QB in the long run, imo.
If the conversation is around guys who HAVEN'T emerged yet, who can be acquired cheaply, and have the potential to emerge as high end QBs down the road, then I strongly believe Dalton belongs in the conversation, and based on your comments, I absolutely stand by my statement that he's underrated.