At the beginning of 2018 tennis player Jack Sock was ranked in the top ten world wide. Sock recently changed his management agency. Sock is now repped by John Tobias in an attempt to restart his career at age 27. Throughout his career Sock has won major doubles titles and many take this move as an attempt to start fresh, SI's Jon Wertheim shares his thoughts on Jack Sock.
More from SI's Jon Wertheim