Barton is spending the season on loan at Ligue 1 side Marseille after falling out with Rangers' hierarchy last summer.
The controversial midfielder was forced to serve a 12-match suspension at the beginning of the campaign after being sent off in the final game of last season against Manchester City for violent conduct.
QPR are facing relegation from the Premier League this term, sitting rock-bottom of the table and seven points adrift of safety with eight games remaining.
Veteran midfielder Derry believes Barton's presence could have lifted the struggling Hoops.
He told The Sun: "There have been times this season where the guys haven't given 100 per cent. So he'd have improved the squad."