Kevin Houser comes to mind quickly. Jahari Evans has been playing lights out and you don't hear much about him even though he is only a rookie. Hollis Thomas can never get enough credit. Scott Shanlee has been our most consistent LB. Charles Grant doesn't get enough love but he is not anywhere near the most underrated. If I had to name one player it would likely be Houser. He is the most accurate lond snapper I have ever seen and he gets good velocity on the ball. Houser is not on the field much but since he has been with the Saints he has had close to a thousand snaps and I can't remember a bad one.
Karney.. I mean alot of people like him but we never hear too much about him or he never gets alot of "LOVE". Bullocks comes to mind on the defense, I think when Harper is back next year this will be a duo to reckon with along with an upgrade at the CB position.