Players like Vitinha do it all really. He's superb technically, and while he's not "powerful", he is extremely tenacious, industrious and constantly moving. I love that sort of player. Pace and power are important tools to have, but not every player has to fit that mold. It just has to be a vein that runs through the team, to give it balance. Players like Vitinha, Neves, Modric, Verratti, Barella, who aren't very big but have relentless energy and technical supremacy are the real difference makers. They give you constant passing options, and close down the opposition very quickly. They are all also what I would call "speedy". Might not be the fastest over a 30-40 sprint, but that's fairly irrelevant in 95% of football. They are however some of the quickest players over 5-10 yards, and capable of rapid and sudden changes in direction.
What we have to do is avoid players who are physically unimpressive. Size isn't a predicator of a player's ability to be physically impactful, as we've just discussed; but workrate, acceleration, and the ability to hold off opposing players, as well as close them down, are. You can't have outright slow players, who aren't physically dominant. That's a duo of death. Because they'll just get bullied. Amad for example is pretty quick, and has superb acceleration. His balance, technique and workrate means he's one of the best players we have at receiving under pressure and holding opponents off, as well as one of the best at closing people down and winning possession in the final third. He's also fecking tiny. In contrast, Hojlund is twice his size, and I would wager faster over 30-40 yards - once they get into a full on sprint over distance - yet he is infinitely worse at those parts of the game. So that just bring us back to technique being such a critical factor. In fact, it's the one constant factor you need, coupled with either pace/speed or power. You can have a very technically gifted player but if he's slow and weak, I fear he'll be eaten alive in the PL or only show a fraction of what he's capable.
Cunha is a good example of a player who has technical ability married to pace and power. Mudryk is an example of a player with pace and power, but very limited technical ability. So the pace and power by itself just isn't enough. You could make the same comparison in midfield, between say Valverde and McTominay. Both robust, extremely industrious midfielders, who are strong with and without the ball and decently quick (Valverde is quicker); but only one of them has top class technique, and it elevates him to a much higher level.
In defence I feel that Yoro and De Ligt are two pieces of a three piece puzzle. Maguire is a capable understudy, but we are badly lacking in that third spot. Martinez is aggressive but actually very poor at physical duels when people go at him. He's great at stepping up and intercepting, but when people try to go past him with pace, he's always found wanting, because he's quite small and he's really slow. His technique in progressing play is what makes him potentially useful, but you always feel like he has a major deficiency. He'd be an exceptional player if he either had (a) that old school Italian defensive nouse that makes him nearly impossible to dribble by, it's a mental attribute much more than a physical one, based on timing, positioning, and reading of the game, or (b) he had one outstanding physical attribute, either good recovery pace, or exceptional physical strength. That would be enough to balance him out as a player. As he doesn't have any three of those qualities, he'll always be a question mark in our back line. If you are completing this team to optimal levels, you would bring in a left footed centre back who is fairly tall, physically robust, decently quick, and can pick a pass. It would be a marquee signing, and it would balance the whole back line out.
I am very much of the opinion that we get players who are the right fit for each position, as opposed to getting the best players we can and attempting to fit them in. This is why I would be sad but also generally understanding of a decision to cash in on Bruno if we get a massive offer from SA. Yes, you'd miss his talismanic presence, but I think it's fair to say that as a CM he has certain deficiencies that make him a less than ideal fit - although I think he can do a very good job there - and our system needs (as Amorim would say) 10's who can play like midfielders but run like wingers. Bruno is a goal threat, both in scoring and creation, and if we played two wide players and a striker, or two strikers, I think he's superb at sitting in that hole and running around wherever he wants....arriving late etc. But our 10's need to run into channels, they need to be able to go past people e.g. run like wingers, but also be able to come deep link up play, connect with the midfield. Bruno can realistically only do half that job.
As a rule of thumb, I think it's a bad idea to sell high potential players at just 20 years old. It's just to be expected that they will have deficiencies. They aren't finished players. They need to be given time. However, if we take the case of Garnacho - for example - here is a player that has tons of pace and acceleration, but is technically inconsistent, very weak, and whose decision making is still very naive and raw. The impacts of that on the team are obvious, because when he plays, the burden of responsibility on him to make goal contributions is quite high, and he's just got too many areas of his game that needs development for him to reliably do that just yet. I think he has a lot of the tools to get there (if he has the determination and work ethic to make it a reality), but he's in all likelihood at least a couple years away from starting to become a more finished player. Ideally.....because he isn't some generational, freak talent like Rooney or Yamal, you'd have his minutes managed and he'd be a player who was in the second line of rotation so he can develop properly without such a burden of responsibility. It has always been how we have successfully developed young players. The likes of Scholes, Beckham, Neville etc., didn't become nailed on starters until they were nearly two years older than Garnacho is now (and he's been doing it for a couple of years already). The problem is that Garnacho is apparently throwing his toys out of the pram that he didn't start the final, and about what his role was. For a player who is 20, in a team that's woefully underperformed, and who has seasoned, older, international quality players ahead of him, that's just unacceptable. So if we were to cash in, for 60m plus add-ons, I would happily make an exception and do so.
Mainoo on the flip side is a player who has sat on the bench most of this season - despite having an incredible season last season - and not uttered a word of complaint. Amorim has said that he has had his struggles adapting to the defensive responsibilities of the newly defined CM role, but that he's also been working hard to develop. We've consequently managed his minutes and rotated him in and out. For a player who just turned 20, that's how you do it. He's a player I am desperate to keep a hold of, because I think in two years he will be a special talent.
If we go for players who fit their roles well, then we have some of the pieces in place already, but we also have some massive deficiencies. We can all debate the order of importance, but regardless of the order it comes in, just to get to having a top quality starting XI, the following positions need to be addressed in the following ways (I would also say that all these players need to be battle tested and approaching or in the peak age window (23-26/7)
GK - A commanding, consistent, capable keeper.
LCB - A left footed, tall, strong, fairly quick and decent passing centre-back.
RWB - A fast, industrious, technically gifted winger who isn't afraid of assuming defensive responsibilities and has stamina.
CM - An industrious and technically gifted midfielder who is equally adept at winning the ball as he is using the ball.
Left 10 - A fast, powerful and technical right footed inside left forward.
CF - A quick technically gifted centre-forward who is a clinical finisher and has a proven track record at the highest level. Must be a good presser/industrious.
That's six top level players to fill all the critical holes immediately. With the remaining squad you could then assemble a very good team with a good balance of ages, experience, and current/potential performance levels.