The reality is, if you cover the NFL draft, specifically:
1) It's impossible to do this with any kind of high accuracy. There are so many players and so many variables.
2) You're always going to be remembered for the ones you get VERY wrong.
3) They're on TV for a reason, they're paid to give STRONGER and MORE OUTLANDISH opinions, for the purpose of driving viewership, readership, and conversation.
The truth is they ARE way more knowledgeable than you or I - because it has been their job to study mass quantities of tape/reviews/stats on these players. They could tell you things about players that most of us would struggle to guess the position of. That, however... doesn't guarantee accuracy.
I think it's more fun to come out here like, "These guys don't know shyt, they just happen to be on TV!" But the truth is, they're extremely well researched... they're just asked to make definitive predictions on a volatile and unpredictable process. Which is why you get all of the boneheaded statements about guys that end up being stars.
I remember when Hoge went IN on Vince Young and predicted he'd be a flop. He got lit on FIRE on this site for about two years, got hammered on the internet, even guys he worked with clowned him... and now, he's right. But was he actually right? Was he wrong and Vince Young just fukked up and lost track of his career?
The one reprieve is that they don't get paid/hired/fired based on the amount of predictions they get right. Once you have the 'expert' title... you get to keep it.
