I am seeing the wood for the trees. He's actually had a pretty patch injury record so the availability may not be as good as you think (though certainly better than Delph, Gbamin!)Itls not a pointless signing if he's available week in week out and allows others to move into different roles.
You're not seeing the wood for the trees here.
I just don't see where he fits into the midfield atm that allows him to be good at his role and allows others to play another role, that's what I mean.
It could maybe work if Benitez played a 4231 with Doucoure as the 10. But it has to be a proper 4231, which Benitez hasn't played and doesn't look like playing, because even at Palace when he switched to that shape midway through the game he pushed Gomes right up to the second striker position, and that isn't a 4231.
Formations only matter so much, obviously, but if you're pushing the 1 behind the striker right up then it leaves a huge gap in midfield.
If the plan was Allan-Doucoure-Longstaff, with Doucoure slightly ahead of the others then in theory I think that could just about muddle through, but we'd need positional discipline from Longstaff and Allan that neither of them have shown so far in their careers.
I'd love to be wrong if he comes and for Longstaff to turn into a Carrick-type as initially suggested, orchestrating from deep. I just don't think he knows how to play that role though. That isn't a criticism as like I say he's good at other things, but those things aren't useful for a sitting player in a 433 shape.