I think it's pretty depressing if any system is apparently that inherently reliant on it's fullbacks of all people. That just suggests to me the rest of the team isn't cutting the mustard.
I made a post yesterday comparing us to Ange's Celtic team. Yes the fullbacks did what ours do - popping up in "free" positions, underlapping runs, getting into the area, etc - but they were more the icing on the cake. The ones who ran the game/system were the two "8/10"'s, one in either half space, and the wingers on either flank.
That's where we are failing currently. We need Maddison to shake off the rust, plus he needs to learn that his job is in the final third, others get the ball to him rather than him coming to pick it up off the centre backs toes. Any of us could do that.
Pape is a likeable lad who brings some things to the table others don't, but at the same time he can't just offer a lot of running, sporadic stuff with the football, and dropping deep and right most of the game... I get everyone loves him, but a lot of the time it's less Sarr, more Sarrsoko. I reckon he could be tried as the back up right back also if we're looking for options, he basically plays in that area most of the game to start with.....
Maybe the realities of the PL won't allow it but a lot of weeks I'd much rather be aping what he did at Celtic and get another creative 8/10 in there and have two options in the final third midfield positions.
Then we get to the wingers, the demands on these guys in this system are pretty big. Top notch acceleration, two way, technically good in their touch/dribble, be able to go past a man, play give and go's in tight spaces, offer short sharp intelligent off the ball runs.... and hopefully plenty of end product. They need to be top drawer, especially at PL level. Really I'd be all for blowing the whole budget on the best we can find for either flank.
Those four positions (plus the midfield pivot, again currently we're having our struggles here which doesn't help us win the battle for supremacy) should be the crucial ones carrying the majority of the threat and incision.