Seems to me the money on a deal has more to do with the market for the particular mold of player than anything else.

The market for Boldin, James Jones mold of WR is consistently less than what fans predict. The "9 route" specialist guys like Mike Wallace and Vincent Jackson consistently break the bank. Cobb is a slot receiver and with 70% of the passes in the NFL right now being in the middle of the field I'd think he'd be a hot commodity. He's not totally proven but he's more proven than Percy Harvin was (although Harvin also appeals to the 9 route crowd as well). I think Cobb is due something on the order of what Welker got. He's still ascending, a little more versatile than Welker, and comparable in character. Welker is obviously more proven and durable so should get more up front.