"I had to play the lad in midfield and he had not had a pre-season game. I brought Kaboul in to play centre-back, but I lost Pedro on Thursday - not that I wanted to but we needed to get some money back in. I also lost Sulley Muntari from last season who gave us fantastic energy.
"He could run, tackle, cover the ground and shoot. He's been a big loss."
Redknapp did not rule out using the Frenchman in midfield again and believes his new signing will improve with match fitness.
Redknapp said: "I didn't bring him in to play in midfield, but the lad needs to get fit. He hasn't had any pre-season games and you need those games to get fit. I threw him in at the deep end and it was difficult for him."