Use him in a correct way and he can be very very effective in our team. I don't want him to be a playmaker or the one to look for to make that final pass in the last third. Get him to play it as simple as possible, without too many touches when standing still/going slow. When he's at full speed and there's space to run in to he's brutal. When we are defending too deep with too many bodies and no pressing and win the ball back and Sissoko charges 70m forward that's when he runs into blind alleys because there's barely any team mates to release a simple effective pass to, because no one has been able to get to the last third quick enough because everyone has been instructed to get back and defend.
I have become very frustrated with him many times, like with many other players, but we've been a fucking mess in every way. I liked what i read the other day, that the coaches are trying get the players to press the opposition instead of everyone sitting back. IF we can do this well and have more players up the pitch when we actually win the ball then our transition from defence to attack could be brutal with Wijnaldum and Sissoko to name two. Hopefully we can add to this instead of selling after making a quality signing. One last thing, i remember seeing Sissoko at Toulouse a few games, and instead of trying to through the back four he often had lots of options to make a simple pass to and then make a powerful run in to the box. He didn't always get it but it did create space for other players. He got the ball back two times after a pass and run iirc, scored one of them.