The discussion is why can some players who are a 10 or an inside forward able to play as 8’s (Bernardo Sliva, Havertz, McAllister, De Bruyne, Foden, Bellingham) examples off the top of my head (I know McAllister is playing 6 atm) and others can’t? How much of it is tactically or position inflexibility or the manager not setting up the team properly.
And yes I am wandering my Mount or Bruno can’t play as double 8’s like the rest mentioned can.
Its not really much different from how some wide attackers can very effectively play as strikers, while others can’t. Or how some CBs can easily flex out to a wingback role and do well, while others simply can’t do that. Or how some players adapt between leagues very well after a transfer, while others adapt slowly or never do adapt to the tactical and physical demands of a new league.
Its usually a combination of that individual players skillset (including deficiencies / weaknesses) and the tactical approach as a whole. What a particular manager wants out of those roles, and what there is around them to support those players, will have a significant impact on the individual players effectiveness. Pep won’t be asking an 8 to do the exact same things as Ten Haag will, and that’s true of almost every manager in the league.