There is a perfect situation where stats don't tell the whole story. Ed Reed was much more than just an INT guy. He was a strong cover guy, not just a centerfielder and when he hit someone he left a lasting impression on the receiver. When was the last time an opposing player said "Damn, that Byrd really hits hard."
I like Byrd, but I don't think he's worth 9 mil/year. Will he have good stats with the Saints, absolutely, but that's because most teams play from behind when facing NO, so they have to throw the ball a lot more.
As was mentioned earlier in this thread the future rides on QB play, if EJ does not become an above average to great QB, the losing will continue. It has nothing to do with Byrd or any other FA we lost. Right now the Bills are doing nothing more than shoring up some positions that need it. The one position I personally, would like to see a decent FA signing would be WR, in my opinion we don't have enough good weapons for EJ right now.