I was never going to draft Manning. No way to know if Griffin would be there in the 8th. A few of my would be picks were taken when I waited a round in League 2. Didn't want to chance it. I rarely care about reaching a round if I like the potential of the player. If I get burned, it sucks, but that's the way it goes. I like to watch the players I draft as well, and well...I've seen Manning do his thing.
As for Decker, I saw a ton of promise in him last season. Now he's got a good QB. I don't like Jackson, and I've had him on my team in the past.
Most of all though, I went for what I think is the better WR, and what is potentially the better fantasy QB. I do agree it's very unlikely that Manning bombs; he's clearly the safer play. Safe is good, but sometimes it's not as fun.
The REAL reason is I need to hopefully jinx Griffin.