As a die hard Eagles' fan, I can tell you first hand that Greg Lewis is an abysmally bad football player. Terribly, horribly bad. Only the fact that the Eagles attempted 60 passes per game allowed him to garner any statistics at all. On any other NFL team, he would never get off the practice squad.
That being said, the Eagles also jettisoned Jabar Gaffney. And somehow the Pats got decent production out of that guy. So maybe Greg Lewis will surprise us all. I highly doubt it though. He's really that awful.