I honestly think that 50-60m is the most I would ever pay for any player, which the odd exceptional circumstance, such as an absolutely guaranteed world class player, or the final piece or two in the puzzle of a nearly complete team, pushing me to 75m. But above that, I’d pretty much walk away from every player on the planet.
The exception to this rule is for a generational level attacking talent that is young, pre-prime, or just entered their prime. Most positions on the pitch require not only individual talent, but critically the importance of functioning as part of a unit. I’d much rather have three 50m midfielders who all compliment each other, that one 100m one, a 30, and a 20, because if it’s respective of their quality/age/potential and other factors, you are much more likely to end up with an imbalanced unit. Very simplified analysis, but it goes to the crux of what I am saying. A midfield and defensive units can, and should, by definition be greater than the sum of their parts. Working together cohesively and synergistically. If you are quoted 100m for an Enzo, you can find another midfielder for half the price that will perform the functions you need him to perform in your system, to a similar - if slightly different - quality.
Huge fees for players who play in positions with very disciplined roles, rarely makes sense, unless they are bringing some transcendent quality. Van Dijk broke the mould for center backs, because he was unlike any other CB on the market or in the world at the time. Combining every quality that would normally be split up between two players. Pogba on the other hand cost a massive 90m, to primarily play as part of a double pivot. It was never going to be worth it. His primary job was to do all the dirty work and simple things really, really well - the stuff midfielders have to do like regain possession, press, quickly and simple recycle possession - and then bring some special quality to playmaking, passing range, goal threat etc. The problem is, you buy a player for 90m, and the tendency to be a superstar weighs heavily on many cases. Like in Pogba’s, he did the spectacular so well, but the routine and simple so poorly. That’s not conducive to a cohesive, well functioning team. His specific role could’ve been filled as well, or better, but a player with a more limited but appropriate skill set, for a fraction of the price.
The rule is that one should only ever pay huge fees for players on positions where individualistic moments and flair are a regular part of their game model. Such as strikers, wide forwards, and wingers. Maybe 10s too, but they are increasingly functional too. We are talking about players where the ability to produce outrageous finishes, best players to disrupt team shape, is not only part of the tactical plan, it’s preferable. For those types of players, massive nine figure fees can be worth it. Your Messi, Neymar, Ronaldo, Salah, Mbappe, Lamal’s of this world, etc etc.
Of the four players mentioned three are midfielders of the slightly more defensive leaning side - especially Caicedo. None of those players will ever justify the fee. It doesn’t mean they will be bad signings, they could be very good signings, but they’ll never come close to justifying the fee, because their roles could’ve been filled to a relatively comparable level by other players at greatly reduced numbers. Maybe they wouldn’t have quite the same “extra” components to their game, but the extra components are strictly necessary for them to perform their core function to the optimal standard.
You’d need a midfielder who breaks the mould, like Van Dijk did, to justify spending 100m+ on a dm/cm imo. A player who performs at such an exceptional level, routinely, and combines the qualities of multiple players into one package, all while performing the core, unglamorous part of his role to the highest possible standard. Of that, the only player I can think of who qualifies currently is Rodri. In the recent past the only other midfielder I can think of who you’d pay that sort of money for as a 25-27 year old, was Modric. Even some of the great midfielders of the last couple of decades, you’d have to ask yourself if they’d be worth the money once they were pulled out of the incredibly cohesive unit that made them so successful? Would a prime Xavi have been worth 100m in United’s system? Or would he have been asked to play in such a way as to negate some of the qualities he showed at Barca?
Grealish was the only player on that list, I believe, that had the potential to justify such a fee. Because he was a potential game changer, who could beat a man and change the entire balance of a game. But he’s never lived up to that potential. He’s been good, at times, but he’s done nothing above and beyond what another, different, 50m player could’ve provided.
In world football if you look at the players who cost over 100m, many of them didn’t succeed, and least not to the extent that people expected. There are only a very, very small group of players who could ever truly justify that sort of fee. Then there are a whole clutch of players who are good enough for someone to demand it, and clubs in need of them enough to pay it; but they stand little chance of ever proving worth the expenditure. Rice, for example, is a fantastic midfielder that improves Arsenal a lot. But in terms of what his actual job is in the system, and how he plays it, he’s realistically “only” a 50-60m player in objective value. Unfortunately, or fortunately for some, many transfer fees take on a subjective nature and are ultimately a balance between how needy the buying team is, and how resolute the selling team behaves. A player will ultimately be “worth” whatever someone is willing to pay for them, regardless of whether the data backs it up.
Some of these fees will start to look increasingly distorted as several summers of PSR restricted spending really takes hold. When a club can pick up De Ligt, Ugarte, and Cole Palmer for the same price as Moises Caicedo, it puts some of these fees into perspective.