* - demote to reserves for a bit
* - give him more games if you're keeping him on the bench and then give him postive praise to baby him a bit
* - praise more players than you criticise
* - finally - usually works but can be costly - give him a new contract with higher wages for 5 years - if you can't offer more money go to finances and adjust budgets to take some money out of your transfer money and pump it in to your wages. You will then be able to offer him more money to meet his demands. As soon as he signs a new deal go back to your finances and pump the money back in to your transfer pot - it won't let you take back more than is required for the wage bill though.
What he is saying is that you rotate the squad or sell players who underpeform too quick. He basically wants you to rotate less or be less harsh with the criticism/sales you have.