The Detroit Free Press' Dave Birkett reported that Mayhew said, "We made a big investment in him, didn't work out, move on."
Young was sent packing after a 2012 that included sucker-punching a teammate, being banished twice during the season after he purposely lined up in the wrong position against the Green Bay Packers in Week 11 and later for insubordination. Then he recently tweeted he didn't want to play if he didn't get the ball and "Oh I'm not done, if y'all going to cut me let me go. I'm tired of the threats."
Schwartz said Young's tweets "didn't have a ton" to do with the release.
The St. Louis Rams didn't waste any time in claiming Young, but that doesn't mean the receiver had any trade value. Everyone around the league knew the Lions couldn't keep him on roster. Why trade for someone who's destined to be released? Young's behavior didn't make him worth it and the Lions had no leverage.
The move leaves Detroit in need of a receiver amongst other positions. Mayhew said the team will be active in free agency.
"We were a non-player in free agency last year so we'll definitely be a bigger player this year," Mayhew said. "We've got to make some changes, we've got to improve our roster and we'll definitely make some moves in that direction."
This is the defining offseaon for Mayhew and Schwartz. They got a pass the first two seasons after being handed an 0-16 program. They turned the corner with a playoff berth and a 10-6 record in 2011 before things regressed with a 4-12 mark in 2012. The Lions have only had one winning record in four years. The pair won't get a fifth season if things don't improve significantly in 2013.
Follow Kareem Copeland on Twitter @kareemcopeland.