The manager seems to have a lot of faith in Lookman and Bolasie should be back before Christmas. I think that RK often sets up a team without genuine wide players in it. When he plays 5-3-2 the width comes from the wing backs.Lookman and Lennon are the wingers left. Bolasie is out. Why didn't Koeman keep Kev this is quite unbelievable.
I think he likes players like Rooney and Sigurrdsson who can operate wide and in a central role during a game.
I think it may also be possible that a player has become available that RK is interested in and leaves Mirallas surplus.
I didn't expect this to happen, I think the new contract was probably to protect the investment but if we look at how little time Kevin Mirallas has been spending on the pitch it may not be such a huge surprise.