This for me
A couple of games ago Bruno took a knock and my heart was in mouth as I waited to see Lingard warm up
As an option to bring on, allow players to rest if we are doing well, at 40-45m it's a no brainer
There is also a very good chance that with better players and coaches around him he takes his game up a level
If Bruno is off for whatever reason, Pogba moves to #10 and either Fred or McT comes in. Seems like people forget we have these two very capable players, who've also had really good seasons, waiting on the side-lines for minutes. We're some way off having to rely on Lingard or Mata to start important games for us.
As for up front, if we bring a quality goal-scoring winger/forward like Sancho, then we already have 5 good players to rotate: Martial, Rashford, Sancho, Greenwood, Ighalo. And while the 6th player (James) is currently underwhelming, he's still a young player on his first EPL season who could well improve and become a decent squad option.
I'm not against signing him, more depth is nice, but I don't really see it as anywhere
near as urgent as people make it out to be. People initally wanted him either as Pogba replacement or as an improvement to Lingard/Mata/Pereira. But the former increasingly looks like staying put and the latter guys hardly get any minutes. And that's before we even bring another winger/forward.