With the luxury of hindsight, it almost holds up.
I'm a former Redskins fan (I'm done. I actually do mean that. When they eventually start winning again I won't be back) who really, really wanted us to acquire Manning that year rather than trying to draft our QB.
I don't think Luck was a sure thing. No QB prospect is ever a sure thing. Sure things only exist in hype and in hindsight.
They really must have thought Manning was done. That's the only way you can justify it. They had no hope that he was going to come back to form. If that had been the case, it would be very defensible.
As it is, though, what they could have had was Greg Robinson, Alec Ogletree, Stedman Bailey, Zac Stacy, Michael Brockers, Janoris Jenkins, Isaiah Pead and Rokevious Watkins? No pro bowlers in that group yet, but a lot of solid-to-good young players. The picks could easily have worked out better. I don't think they'd trade Luck for that group today.