Moving last minute, finding it hard to find a place in the new club leads to low morale which in turn leads to bad play. Players are human as well, they are affected by bad press and abuse from fans
I want to see Sissoko want the ball. Eriksen always goes after the ball he literally yearns for it at his feet. I'd like to see what a Sissoko brimming with belief in his own ability can do. Yesterday I saw genuine effort which was great to see. He didn't hide he tried to do things. If he keeps doing that it will click and he'll give our first team an absolute brute. Watch him launch a 30 yard rocket for his first for us sooner rather than later.
The great ones have no fear and Sissoko should have faith that if he tries to pull something off and it doesn't materialise that we have enough top class defence minded people to make up for it.
That being said, especially in home games he'll probably get bombarded with moans and groans if he tries to create and loses the ball. Leave off of him if he does (the same with all of them), your 'support' will do more harm to the team than good.
Encourage him, it's a supports job to give the players needing confidence a bit of encouragement to keep giving it a go