This. Can't over-stress this. Part of good coaching is take players and elevate them beyond perception. This is what is happening under Poch at Tottenham and what always used to happen under Fergie over here. If we can't do this properly, then no amount of transfers is going to do us any good. Remember, players also want to be under a manager who can improve them, which is why you have players wanting to play for Guardiola and Klopp as of now.
De Gea, Shaw, Lindelof, Dalot, Pogba, McTominay, Martial, Rashford, Lukaku - that's a pretty decent spine right there. Add to that players who can improve in Fred, Bailly, Sanchez, Lingard and it's not that bad, just not that devastating. The point is to complement the current squad this season, and fill the gaps. And then improve upon it the next season. It's a slow churn.
Also, let's be realistic, No way are we improving the complete overall balance of the squad in one window. We don't have the resources, nor is it realistically possible. Get players' fitness up, motivate them and get them back on all gears again. Honestly, I don't think we have that bad of a squad as last season made us sound. Key transfers, and top-4 isn't a problem, but reaching City and Pool is, which we have to build for from then on.
Also, fitness, I'm still puzzled as to what Mourinho was making them do. Literally no conditioning at all, almost like he was getting them fish-n-chips during that time and asking them to stay back instead of run.