I think many who fell in love with United did so because of our style of play. Two great wingers who, although different in their own ways, could contribute with goals, crosses, dribbles, speed and creativity. Now, we don't have wingers. Martial is not a proper winger. Rashford is a striker; Sanchez is more of a hybrid these days; Lingard prefers playing through the middle, as does Mata. Valencia and Young are converted to fullbacks.
I just read that Rosenborg, the dominant team in Norway for the last 20 years or so, have fired their manager (7 out of 9 trophies not good enough). When looking for their next manager/coach, they will demand that he plays Rosenborg's 4-3-3 system to continue their style of play. At first I thought this was a little strange, but then I thought it makes sense. A club should have an identity. For Rosenborg, it's their 4-3-3 style. For United, it used to be great wingers and 4-2-2. Then we signed Moyes and he actually continued with wingers and crosses, but well, we all remember how that turned out. Then we signed a completely different manager with his "philosophy". Unfortunately, I think this messed up United considerably and was too much of a revolution instead of an evolution of a club of great traditions. Now we have Mourinho who is a different manager, but still he is not perpetuating the United identity.
Before anyone points out, I know even Ferguson tried many different tactics and was not a stranger to ditching 4-4-2 whenever the opposition demanded it, but there was an identity to our play that I don't think require a set formation. Arsenal had their style of play with a clear focus on a very solid midfield. I actually think our central midfield was just as strong (Keane-Scholes, Scholes-Carrick), it was just overshadowed by our wing play and attackers. Since Ferguson's last signing, Zaha, we haven't really signed wingers anymore.
We sign attackers and try to shoehorn them into a LW or RW position, and instead of offering width and creativity, we congest the middle and every defender on earth knows that every attacker we have will try to cut inside. We could do that with Dybala or Griezman as well, but I doubt it would make us better. If we are to sign a new attacker, and I genuinely think that is much more important than another CB, we need to look at what kind of player will give our attack identity and balance. We need an attacker or winger who prefers playing from the right. He doesn't have to hug the touchline like Kanchelskis or Giggs, but he needs to prefer to play from that side. Dembele or Pulisic perhaps?