I think Rashford would look better in a counter attacking side. He doesn't have the technical ability to play in a more possession orientated side. It would be interesting to see if ASM could perform as well in a more possession orientated side where he would have less space to dribble in. Put it this way ASM would look worse than he does now at Utd, but Rashford would look better at Newcastle. That said my money is ASM being the better player.
It depends. It's an argument that holds truth, but, given Rashford's current (or not so current) form, it needs a deeper assessment (i'm writing this knowing full-well that, if we opt for a counter-attacking style tonight and he scores, some will be out for blood in this thread).
Good possession-based sides don't usually go after players like Allan Saint-Maximin. Or, to put it better, they usually perceive them as stop-gap solutions to systematic issues that can't be fixed overnight. Adama Traore's brief stint at Barcelona can serve as an example: A team that seemed rudderless on the pitch and lacking in quality in many areas, and a new manager with a huge rebuilding job at hand. Too many holes to patch up in one go. What Traore could give them was an outlet in the build-up whenever they weren't able to short-pass their way farther up the field, plus an injection of pace in the final third that could lead to a quick and easy cross/cut-back pass in the box. That's probably how ASM could find himself in a possession team.
Given that, i don't think he would look worse in this United side because, however you want to look at it, we are a team that wants to make the transition from a counter-attacking side to a more possession-based one. The problem is that we simply suck at it at the moment. In that sense, and if Ronaldo stays, (someone like) Saint-Maximin would benefit us more in the short-term. Better dribbler, better ball-carrier, not so easily dispossessed. To say it plainly, he could prove to be more useful in the middle third, where we struggle to move the ball vertically, and in the attacking third up until the edge of the box, where his ability to draw defenders can generate pockets of space we aren't able to create via passing at the moment. Not a long-term solution, but one that could make the transition smoother (or not so hurtful as it seems nowadays).
Rashford, or rather the current version of him, could make Newcastle look more threatening on the pitch. But i don't think he would do it immediately. Part of it is because i don't think he would displace ASM in their line-up. If anything, he would thrive lurking at the far post while ASM does his thing, waiting for the cross or the switch-ball to attack the space. Rashford would eventually replace Almiron in their starting-xi, but in the near future. Right now, they need the Paraguayan's energy levels, his defensive contribution and his movement around the box. When Newcastle's set-up improves and becomes more balanced, then they will be able to replace hard-work with end product in one (or more) position on the pitch.
So, as you argue, ASM seems to be the better or the more useful player right now. The irony in this is that, many things that ASM does on the pitch for his team, Rashford has done them better at the start of his career. He could run with the ball through the lines, he could find the angle for a finish in the box while running at defenders, he could use his weaker foot (to an extent), he could get past people, and he could come up with the goods on both sides of the pitch. But for some reason - injury, mental issues, fame... take your pick - he hasn't been performing well for quite a while. The worst thing, what's coming out from his camp in the form of leaks to the press, serves as an indication that he has "convinced" himself he should be nothing more than a striker who doesn't want to play centrally. That he doesn't "need" to contribute anything else. Just like Ronaldo at RM, he should be on the pitch to score the goals the rest of the team will create for him. The problem is that United, so early in ETH's tenure, could use more heavy lifting than entitlement/pushing a player to be something he can't any more on the pitch. And when you give the manager not one, but two players who contribute nothing more than goals (Ronnie, the second one), you're not making his job any easier.
Coming back to the bolded part, the real question isn't really how much space does he need to operate into. Whatever football you want to play, a good goalscorer who times his runs in-behind to perfection is always needed. But when you're playing for the top dogs, the pockets of space are always hard to be created. Nevertheless, the best teams know how to generate them. Just like De Bruyne saw an impossible pass to Bernardo yesterday. From that point, it's about vision and execution. Not a matter of space, but a matter of time. To see the opportunity and grab it. How much time does he need? During his prime in Madrid, Ronaldo was the best the game has ever seen in that particular department. How good is Rashford in that aspect of his game? Answer this and you'll know if he has a future as a top player in a top team. If you think "not good enough", Saint-Maximin is already the better one of two players with a rather low ceiling. If you're still on the fence, you'll probably reserve judgement for a couple more years.
