The reason our attack play is poor, I don't think is actually because of our attackers.
I actually think our issue is that we cant sustain attacks because as Rangnick rightly put, we get flipped over on transitions so easily.
You can see the press is triggered when oppositions pass to the full backs, but the full backs always drill a pass into midfield where our midfielders fail to regain possession on heavy touches or they read the game poorly. Zakaria would help a lot in the decision making and off the ball work. His pass rate is really impressive on top, which we desperately need in the middle with McFred and Bruno carelessly throwing the ball away.
We have the right players offensively, I think we just need to keep the game in the oppositions third to allow them to keep sustaining attacks. But if the 3 behind them are considerably leaky then it ends up being a wild west match. That's why Rangnick put 3 in the middle and then changed to a diamond vs Villa. I think he's right to recognize it as an area of where we need to improve to control and therefore attack.
I think that is a seperate problem with our attack, one I do not dispute. IMO our real issue is attackers can't keep the ball high up the pitch, let alone create chances. Rashford runs down blind alleys, Greenwood is one dimensional, Sancho is still adapting and is sloppy at times, while Bruno is horrifically out of form. On top of that, the wide players aren't really on the same page as full backs. So all of those things lead to easy turnovers and buckets of space our midfield can't protect well enough to stop us getting broken on.
Whilst I agree Zakaria could help us in one regard, I'm not convinced that he adds enough value to us right now to gamble on:
1) Having the same potential prior to his injury
2) Him being a significant upgrade in quality (Bundesliga tends to be very hit and miss)
3) Adapting to the league
4) Adapting to a squad in as poorer form as ours right now.
Anyway, if we get a few players out on loan or sell, I think the above is worth gambling on for the price. I just can easily see why we're not just pulling the trigger right now.