I think it is very hard to rank. The position you might get away with crap the most is attacking midfield probably. You can still defend and if you got a clinical striker and some good wingers you could still score and create. People might not think we get away with Lingard and Pereira, but they do not normally cost us the games and Rashford could still score a lot.
Second would be one winger I think. If you got one top winger and the other is poor then that could still work. Although teams might focus on stopping the other wing.
Still we see weaker teams often having one good winger and still getting fine results. Leicester won the league with one top winger in Mahrez.
Third would be striker, but it would need other players to get the goals. You see teams like Sheffield, Newcastle grinding out wins without strikers scoring goals. It is not pretty and boring, but it can work.
Although to be great then I think the midfield is key. That is what allows you to dominate the games and stop being dominated. Wingers can also raise a team a lot doing multiple things at the highest level. Barcelona under Pep showed what a top midfield could do. We see it with City now as well and Liverpool in a different way.
Kante was massive for Leicester when they won it and for Chelsea when they won it.
Least important is central defenders for being a top side. They are important, but it is most easy to carry crap there if your squad is great. They are the least important in attack even if passing from the back can improve your side. If you defend well as a team you can still win many games. We have seen it with City a lot although they have struggled more this season with less cover in front of them. A great leader like Van Dijk can be key still, but you can have a Lovren with him and still look great.
Two crap central defenders normally hurt you, but if the rest of the side is great you can get away with it more than other positions. This is for top teams that dominate the games. For mid table sides central defenders are more important in order to deal with crosses, set pieces and holding the team together.
Having a great striker can win you a lot, but only if you give them decent service. Although some strikers can do things on their own just like the top wingers.
Fullbacks being crap in attack might not be super important for smaller teams, but if they are crap at defending you could get destroyed on the wings if you play against top wingers. We see that with some of weaker teams in the PL. Attacking fullbacks is also key for top sides.
I think the most potent players to raise a team is players like Hazard, Neymar, Mane, Rashford, Messi, Ronaldo. Great on their own with unique abilities that can function even with poor players around them. To raise a team with decent players a guy like De Bruyne, Pogba, Di Maria, Coutinho, Mueller, Özil (in the past) etc might do wonder.
Defensive midfielders are key, but there are more players around that could do a great job compared to more attacking players. Although put crap there and you could get destroyed. We have seen Arsenal doing it for years.
