He's shy because he's in new country and a new club, not because he lacks mental strength. Dude is Brazil's #10 (now #11), first choice player for Chelsea, made a fool of everyone in the UCL and turned Pirlo's black beard into a white one within one game and then made Buffon such a fan that Buffon got a tatto of Oscar's face on his arm (rumours are that Oscar himself inked the tattoo while he was doing keep ups with 3 balls). Now that's mental strength.