By these rules, if you have two 90 players in any one position, one of them will eventually develop concerns because it's impossible for both to play at least 65% of the matches as 65+65=130%.
If you have any 94+ player he will definitely develop concerns as it is IMPOSSIBLE to play 80% of the games due to fitness loss. Same goes for players rated 92+.
More, if your 89 rated players expect up to 40% of the matches and they are substitutes for your 94+ rated players, they will obviously develop concerns as 40+80=120% !!
For anyone able to do basic math this will lead you to have only a team with under 89 rated players for substitutes and a main team composed by 89 and 90 rated players to avoid concerns.
If any of your players goes from 90 to 92 or 94, you have to sell it immediately to avoid it developing concerns and losing value. Anyway, your top 5 players (don't know how you pick it from a team with some 6 or 7 players with the same rate) will eventually develop concerns.
All major teams are composed by 21 to 26 89+ rated players. All those teams will eventually have to deal with concerns. Can you tell me how on hell is this solving the problem of teams having a 150+ player squad ? Is the real life Real Madrid/Barcelona/etc squad a player hogging squad with lots of unhappy players ?
Each change made to this game gets it one step closer to having no players at all. New interface, new prizes/player values, new concern system, the list keeps growing. Good job.