There is no doubt for Irish first five-eighths Jonathan Sexton.
Ask him about progress in his game and he fingers the input from his Leinster coach Joe Schmidt, the New Zealander in charge of the champion Irish side.
"It's everything about him, his manner, how much he knows, the detail and analysing the opposition and preparing you. He does everything with a smile on his face," Sexton said.
He admired Schmidt's consistent demeanour, which was not always a dominant feature of rugby coaches.
"It's not surprising they want him back here," he said.