The midfielder moved to Fratton Park on loan for the remainder of the season last week and made an encouraging debut in the 2-1 win over AFC Wimbledon on Saturday.
Despite being a key player when the Tykes achieved promotion from League One last season, the ex-Luton man fell out of favour following the appointment of Struber as manager in November.
McGeehan made just two substitute appearances before being omitted from five match-day squads.
And despite Struber rating the 24-year-old, his duties off the ball were why he slipped down the pecking order.
The Oakwell boss told the Barnsley Chronicle: ‘He is a very good player. But, in my style, we need players with more activity against the ball and I think he must learn to work against the ball.
‘This is very important task for my style and other players in my squad are, in this part of the game, further ahead than McGeehan.’