Laalaoui isn't a DM though, he's more in the mould of Slater/Puerta. Zambrano I'm not sure suits the sitting deep role either.
I don't necessarily think the personnel are the core issue at the moment, it's more the tactics we're playing. Our main philosophy (when everybody is fully fit) seems to be "get the ball to the wings and whip it in for McBurnie". Without Oli, we rely more on balls over the top for Gelhardt to run onto because we don't have faith that Destan/Joseph will be there. Oli also does a lot of work dropping deep to start attacks off and then gets up the field, which help out the midfield if we're being swamped.
Whatever we do, our midfield is often completely bypassed when we attack and when we are out of possession, the opposition attacks often come down the wing so the central midfield isn't directly involved. Outside of the mistakes we seem to keep making in the back line, most of the goals we concede seem to come from our full back positions, usually because Giles and Coyle have pushed on and left a gap, while the wingers aren't getting back to support them.
What our midfielders need to do is press to choke the middle of the park so that the ball goes out wide, but we can double up on their wingers by having our fullbacks and wingers mark them. At the moment, our midfield is very static, so once the ball goes past them, they can't get back in time. They're reactionary as opposed to being proactive. Crooks for me is the weak link when he plays further forward - the fella can pass a ball great but when he tires, boy does he tire out quickly and becomes very sluggish. Slater has the energy and technique, but often rushes when a simple ball will do. Hadiziahmetovic can pass the ball brilliantly, but is too causal and used to being given more time. Gyabi seems ok when coming on as an impact sub but from the start he often looks lost. There isn't really anybody in the midfield who acts as that dominating force or focal point for everything. Seri came close to that most recently, a player that in both attack and defence dictated what our midfield would be doing.
What we need is to repeat that - somebody who has experience, technique AND defence awareness but is also mobile enough to get on the ball when we need to drive on. And with an embargo in place, that's going to prove very difficult unless one of the current lot can take on that role. Slater seems the obvious choice, but it'll take a lot of conditioning to make it happen.