The Ghana midfielder joined on a free transfer after FIFA approved his exit from Ukrainian club Dnipro.
Boateng started in the opening day win at Sunderland, but has not played since and he was not even amongst the substitutes for the weekend defeat at Chelsea.
"On the bench I have to make decisions, like can they play in different positions," Jol is quoted by the Fulham Chronicle.
"Derek wasn't even in the 18 for the last game.
"He didn't play for a year and it showed. He was good in the first hour [at Sunderland] and then he dropped a bit."