The 29-year old striker is out of favour at Villa Park and former goal scorer Withe feels it might be the right time to move him on.
"There's loads of speculation about the transfer fee and all that but, at the end of the day, it's about you getting into the team and performing," Withe told the Express & Star.
"When you go from being the main goalscorer to being on the bench, it has an effect on you mentally. When he was signed for big money Villa didn't have anyone to score goals, so he was the focal point in the team.
"All of a sudden in football, different managers have different ideas about players and he's maybe not seen as an integral part by Paul Lambert."