The problem is that even prospects that "simply can't fail" simply can, in fact, fail. Check out Reggie Bush. Or Benson, Brown, and Williams. Or Braylon Edwards, Charles Rodgers, Peter Warrick. Sam Bradford, Tim Couch. Ryan Leaf. Robert Gallery. Glenn Dorsey. Courtney Brown, LaVar Arrington. David Terrell, Roy Williams (WR version), Mike Williams (OL version). I'm sure there are a lot of other names that aren't immediately coming to mind. A surprisingly high number of "can't miss prospects" can, and do, wind up missing.
I wouldn't say Bush has been a bust. Minor disappointment, but not a bust. He's actually been a key contributor for a ppr dynasty team of mine that's made the playoffs for something like 5 years in a row. And he's still going strong in FF and NFL terms. Brown/Benson/Williams were not can't-miss prospects. Anyone who touted them as such was way off base. That's not just hindsight speaking. They all had warts. The 2005 draft was soft. That's how a guy like Braylon (who couldn't leave after his junior year because he would've been the 4th WR drafted) ended up as a top 3 pick. Just a soft group all the way around. Alex Smith. Ronnie Brown. Braylon Edwards. Not a can't-miss prospect in the bunch. There is a difference between guys like Luck and Richardson, who would be the first player picked at their position in any draft, and guys like Smith and Brown, who just happened to be the first player picked in their particular draft. This is a very important distinction and it's usually pretty clear if you watch football and follow the draft closely. Calvin Johnson was a can't-miss prospect. Keenan Allen...not so much. It's a moot point because the risk of busting is offset and then some by the potential for a longer career. Drew Brees is almost 11 years older than Andrew Luck. 11 of his NFL seasons are done and gone. Luck has his whole career ahead of him. If we expect Brees to play for another 3-5 years and Luck to play for another 8-15 years, then Luck only needs something like a 50% chance of becoming a superstar to have more career value than Brees. This is an oversimplification of the math, but the general idea holds. And if Luck has closer to a 65-75% chance of reaching that level (which I think he does), he suddenly looks a lot more valuable than Brees (which I think he is).
"Minor disappointment"? Bush was being drafted with the first overall pick in startups before he'd ever played a down. He's finished 17th, 24th, 35th, 33rd, 62nd, and 13th in his six seasons so far. Bush has been a major disappointment. And I'm fine if you want to say guys like Brown, Benson, Williams, and Edwards weren't "can't miss", but no amount of spin will hide the fact that any list of truly, absolutely, positively strictest-definition "can't miss prospects" will include Charles Rodgers, Glenn Dorsey, Robert Gallery, LaVar Arrington, probably Peter Warrick... Lots of guys who missed, some spectacularly.I agree with your general point, though- if Luck has a 50% chance of becoming Brees, and twice the expected career remaining, then the EVs should be the same. I put Luck's chances of becoming a fantastic QB at higher than 50%... But his chances of becoming Drew Brees? Drew Brees has finished in the top 10 in overall VBD 4 times in the last 6 years. Not top 10 at QB, top 10 across all positions. In order for Luck to reach Drew Brees's production value, it won't be enough for him to become a phenomenal QB. He'll need to become one of the top 10-20 QBs in NFL history. I'd put his chances there at considerably below 50%. There's a large window between "awesome QB" and "fantasy uberstud". If Luck is the next Steve Young, trading Brees for him would be a coup. If he's the next Philip Rivers... yeah, not so much. If you would be willing to go to Vegas today and put $1000 on Luck to make the Hall of Fame with even odds, then sure, trade Brees for him. Otherwise... well, I'd still rather have Brees. Next year the calculus might be different. Two years from now it will certainly be different. Today? Brees.Another thing to consider is the advances in modern medicine. 30 years ago, an ACL tear was a career ender. 10 years ago, it was 12 months to return to the field and 24 to be productive. Today, we see guys like Peterson and Welker make a mockery of that timeline. Based on historical precedent, Brees might be nearing the end... but how long is historical precedent going to hold up? If Brees falls off the cliff at 37, Luck looks much more appealing. If Brees hangs on until 41, though? His best trait, his accuracy, is one that should be relatively impervious to Father Time's ravages. Is playing and performing into his 40s really that far-fetched?