panthers-
That's a bad example. With the year he is having, it would be foolish to trade any of his cards right now. My example would be Adrian Peterson. His cards are Hot right now regardless, but some did drop off when he got injured.
As for your triple jersey, I researched it, like you probably did and found 1 card. If you want to go by "sell value" you can't set it from 1 card sale. In that case, I could say a DeShawn Wynn auto sold in his hometown for 50.00, so I want 50.00 in sell value. It's a ridiculous thought process.