Just '08, or are you talking about the five-year period. His best regular season wasn't even tops in the NFL at the position — Andre Johnson had over 100 more yards.
Similar production at more impact positions:
DeMarcus Ware, OLB
Jared Allen, DE
Adrian Peterson, RB
Drew Brees, QB
Peyton Manning, QB
Similar protection at similar impact positions:
Andre Johnson, WR
Ed Reed, S
Patrick Willis, ILB
Champ Bailey, CB
Joe Thomas, OT
Troy Polamalu, S
Those are 11 guys you could throw into the bingo shaker with Fitz and argue about. Boldin never even makes the list.
I guess you'd have to ask what five-year period are you talking about—when it comes right down to it. Fitz has been a great player,but it's hard to be an elite WR when you don't have anyone throwing you the ball. It's exceptionally difficult to be a Top 5 player in the NFL at WR when you don't have anyone throwing you the ball.