Do players not 'indispensible to the club' play worse than thos who are ?

Feel free to think of it as another speopleism.

But even in my early days of playing CM4, it seemed apparent that my players who weren't 'indispensible to the club' would make more mistakes/play worse than those players who were indispensible.

Given that on that version, you could swap your players status around willy nilly without any consequence, but that on FM2010 a player will get unhappy if you lower his status, does playing worse/better according to squad status therefore have any basis in facts ?

Wouldn't that be the reason they aren't indispensable?

Not directly, no, but you'd logically give your best players the highest squad status.

I'd be more inclined to make my star striker a key player over a youth prospect from wherever. As the star striker is good enough for my team then i guess he deserves the higher status.

They're not going to play worse if you downgrade their squad status its simply that the best players are the ones who are indispensible to the club because they are better than most of the other players in the team.

They may get upset, which would affect performances for a short while, but they'd get over it and play to their attributes again.