See What Mourinho has to say about Costa's Bad Behaviours

In 13 premier league matches, Costa has picked 7 yellow cards. Bad! Even myself am so angry with the development. Even after serving a suspension, he has played 2 premier league games- and out of which he collected 2 yellow cards.

One begins to wonder why good players behave this way, well hear Mourinho speak into the situation:

"I can't believe it,I can't believe it. I remember two that are understandable and fair."
"One was against Newcastle because he complained with the referee with arms in the air in body language that was not accepted normally by the referees and [Martin] Atkinson gave him the yellow card.

"And the other one in Liverpool, when there was a really aggressive duel with [Martin] Skrtel - you know, fighting in a yellow card way.

"All the others, the first one at Burnley is a penalty and a red card for the keeper and he gets a yellow card.
"Other times, it is not a simulation and they give him a yellow card. Other times he touches one guy and it is a yellow card.

"Everything he does is a yellow card, so he does nothing for a red card, he does nothing, really.

"For me, the normal situation would be now to be on the second, maximum third yellow card. But seven yellow cards - it looks like everybody comes ready for him, which I don't understand."
-Mourinho
Source: Skysports.com