Without Humphrey, the Packers found themselves thin during practice Sunday morning at the position. Veteran Bubba Franks did not practice, and reserves Zac Alcorn and Clark Harris were out with leg cramps, leaving Donald Lee as the lone tight end.
General manager Ted Thompson said after practice that the team will be seeking a tight end to fill Humphrey's spot on the roster.
"Individually, you feel bad for Tory because of the type of spring he's had," Coach Mike McCarthy said. "You hate to see something like that happen anytime, but more importantly on the first day."
Humphrey played in seven games last season, mainly on special teams. He sustained a hamstring injury Nov. 12 at Minnesota and was placed on season-ending injured reserve three days later.