To be fair, I think the narrative is more Martial isn't a world class no.9, in the same bracket as Kane, Aguero, Lewandowski etc. Fair enough, he's not, but its lazy to suggest that because he's not world class, then we should be looking to bring in someone else. Selling RVN and giving the reins to Saha, Rooney and Ronaldo is case and point. I feel Man Utd have always been better when the forward line is thought of as a unit, rather than one prolific player always being relied on. We have that dynamic with Rashford, Greenwood and Martial, and hopefully Sancho incoming.
In terms of the team itself, he's developing a really good understanding with Rashford and Bruno, and you can see he's always been on the same wavelength as Pogba.
I don't necessarily disagree with the view that Kane would take us to the next level going forward. In fact, on current form Martial stays in the team anyway and Rashford likely drops out. It's moreso the fact that that transfer is just never going to happen, and ignores our glaring weaknesses in the team (RW, CB and CDM) so you're just sitting there and wondering how the hell upgrading on one of our better performers will solve all of our problems. It's as if when Mourinho pushed him out of the team, he became the media's poster boy for what was wrong with United, when in reality what was wrong was the fact that he wasn't in the team in the first place ahead of Sanchez/Lingard etc.