I don't know... perhaps it is about fighting spirit and who wants it more. I maintain that several things, like challenging for the second balls and winning your duels, playing with your back to goal or on the half-turn, which for some people are just prerequisites for a footballer, are, in fact, qualities that a player either possesses or he doesn't. If, for example, you expect Martial to spend 90 minutes "getting stuck in" and outmuscling two defenders breathing down his neck (like Drogba did back in the day), you'll be waiting for a long, long time. It doesn't make him a loser or a weak personality, though. That's who he is as a player.
It doesn't mean that player x, z or y is a bad player. Most of them possess standout qualities. It's just that very few of them are decent "all-around footballers". This, more often than not, produces a "moments player". A footballer who will come up with the goods as long as the whole team caters to his strengths and/or the opponent suits his style. Which, again, is something that happens in football and is also one of the tasks a manager has to deal with. Ancelotti is probably the best in the history of the sport at it. The problems start to arise when your squad is filled to the brim with such players.
Most people have realized, by now, that we need to "control" games better. The lines must be pushed higher, the passing in the centre of the park must become more intricate and, ultimately, the possession in the final third has to become better. While working towards that, some people on here, kind of see that a player like Antony, despite offering little to none end-product, actually brings something to the table, especially when it comes to keeping and recycling possession higher up the pitch. And while his end-product is a valid concern, he's being appreciated more than he should because the rest of the gang are godawful at it most of the time. Remember that this is the goal most of us agree we should be working towards. You see the contradiction here?
It's funny that you mention Real Madrid because, in a way, they are the perfect example. Under both Zidane and Ancelotti, they have always been a team with glaring weaknesses in the game. But they make up for it because they always find a way to build a team around solid constants. I'm not talking only about goals and assists. Kroos and Modric is one of them. Their intelligence and passing abilities allowed their managers to design working solutions in the midfield (Di Maria, Isco, even Valverde). But it's not just them. Benzema's world-class off the ball movement and Marcelo being basically a play-maker on the left wing (and one of the best LBs in the history of the sport) allowed Ronnie to play to his absolute best. Now, they have Vini Jr, who's probably the best in the world at carrying the ball from the middle third into the opposition box and Benz has proven that he can be relied upon when it comes to scoring. They are the "enablers" of their team, they possess the skill-set to deliver against all sorts of opponents and under various circumstances. And this is what breeds confidence to the rest of the team.
United used to have these players throughout Fergie's reign. In his later days, they kept winning trophies despite most of them being way past their best. Rio/Vidic at the back, Evra covering the whole left flank, Carrick and Scholes/Giggs in the midfield, Rooney operating between the lines. We won the league and reached the CL final with Hernandez up front and with Berbatov out of favour. People today would be screaming about how many new players we need to challenge.
My biggest fear is that the people who run the club believe that they have these players. That we just need to add a couple more and we'll be fine. I sincerely hope this is the case. Pep mentioned something interesting after we beat them at OT. He was asked if he believed that the gap between the two sides had been narrowed, and his answer wasn't a simple yes or no. He said, instead, that United are still a transition side (meaning that he has been dealing with that since 2017). Which is true and it has nothing to do with ETH's coaching abilities. He's a far better manager than Solskjaer, but the fact remains: We were a team that passes the ball to Bruno so that he can play the first-time ball in-behind to Marcus under Solskajer, and we are still a team that does the very same thing under ETH. Perhaps, just saying, this is as far as we can go by doing just that.