Dialing it down to singular characteristics like 'pace' and 'power' doesn't really capture the problem. Most of the teams we struggled against, got diced by Tothenham. They didn't have much power up front. What they had was a pressure high mentality, and an abundance of technique.
Pace slowa down when technique is lacking, power weakens also. Josy Altidore and Bony are good examples of the latter. What we need is an abundance of technique, and vision. Dribbling technique, ability to take on 2 players thus disorganizing defenses. That's what Boufal or Asensio will bring. Superior dribbling and passing technique from the wide areas. Superior ball control in the middle and clinical finishing up front. The clinical finishing we have in Aguero and DeBryune. The central control we are half way their with Gundogan, if we ad Kroos or Isco or Thiago ( or unbelievably Pogba) our control of the central mid area will be suffocating.
The last thing we need to be adding is another possession breakdown component. And that is what Lukaku is. Benteke is superior technically to Lukaku yet Kloop has wisely gone away from him, because he sees the obvious. Unless you are in a last ditch situation and want to lump the ball forward in the last few minutes. Simply these are not the right players for a technical team.