Here is what Mats had to say:
Some claim Federer’s mentality is wrong and that he is too friendly with Nadal. Federer produced a surprisingly calm facade after a 6-4, 6-4 loss to Nadal in last month’s Monte Carlo final.
“Roger looked too happy after that defeat,” reckoned Mats Wilander, the three times former French Open champion. “He should see that losing to Nadal is unacceptable.”
Wilander suggested Federer should release some of his emotional control and get angry, although given the embarrassing problems Federer had in keeping a check on this emotion before he reached maturity, it seems unlikely he will risk it.