Grimes plays the role Allen has been playing but can be more progressive than Allen. Most of his passes as short and aimed at ball retention in a CDM role. It's just that unlike Allen if the longer ball is on Grimes can play it.
He'll also allow us to go forward quicker than Allen, there has been one or two times Allen has taken the safe 5 yard pass when a longer ball could have been one. Grimes if he signs will play that pass.
He's good, he isn't going to run around diving into tackles but he'll make us a much more coherent attacking team with how he can progress play from deep.