I think it is WAY early to call him the next Ryan Leaf, and I wouldn't make any judgements based on his first playoff game.
But I also think it's WAY early to call him great.
Peyton was a LOT better in his second year than Eli has been. He was one of the best QBs in the league already and it was clear he was special.
Eli isn't in the top 20 his sophmore year.
Before I get jumped on, I don't think that this means Eli WON'T be great, just that he ISN'T.
I think he could go either way, frankly. Not Ryan Leaf, obviously, that's absurd, he's already surpassed that disaster. But I do think he could, in the end, be an average NFL quarterback or a great one. I think it's too early to make a judgement either way.