 Complete the following phrase:  Button was joined at McLaren by Ferrari Driver Academy graduate Sergio Pérez for and their relationship was cooler because the latter entered the team hastily. He was appointed a director of the Grand Prix Drivers Association GPDA in March 2013. McLaren built the MP4-28 car not in advance of regulation changes for , but from scratch. This caused Button to drive an unstable car with understeer, a lack of downforce and severe tyre degradation. After finishing ninth at the season-opening , McLaren introduced components from the MP4-27 onto the MP4-28, which had no significant effect and Button continued to attain sub-par results throughout the season with a best of fourth at the season-ending . He was ninth overall with 73 points. Button was involved in aggressive driving from his teammate Pérez early in the season in 