Holdsworth told BBC Radio Nottingham: "We've fallen away [from the play-offs] in recent weeks because we haven't had the ability to win games.
"It's about players having to step up, so there are one or two there who may have to go."
Holdsworth said: "I only want characters who have got that willingness to be able to understand the game - it's not just about brute force and passion.
"I don't think we've been strong enough in the centre of our defence throughout the season."
Stags were relegated to the Blue Square Premier in 2008.
Source: BBC Sport
Source: BBC Sport