If there are only one or two players really suited to high pressing, the team can't do it. We've seen what happened with Fred earlier in the season for exactly that reason - he'd press high, the opposition would pass around him and suddenly there would be a huge gap that they'd run into where Fred had left his position while everyone else was sitting deep.
We can cover for one or two players who don't press massively hard, although they would be expected to do more than they do in our normal sit deep and let the opposition come to us style. Martial against Arsenal was the perfect example. He pressed fantastically at times, far better than he normally does. The reason that he could do that is because the rest of the team was also doing it, getting our entire team on the front foot and making it easier for Martial to do it both physically (he wasn't having to also run all the way back every time we lost the ball) and mentally (yes that is somewhat a sign of weakness with him, but it's important to know how to get the best out of your best players).
As such, if the only 'lazier' players we had in our front six were Martial and Pogba and they were surrounded with the likes of Herrera (probably the most important person), Fred, Pereira, Rashford, Lingard and Sanchez, it should work well. But if not many of those players are playing and we're instead putting out a lineup mostly made of Matic, Pogba, Martial, Lukaku, Fellaini, McTominay, Mata, etc...we're not going to be able to press properly and it's exceedingly likely we'll play slow boring football.
