sidelined

Mark Philippoussis is undergoing career makeover umptybillion, this time taking the Andre Agassi approach by playing challenger and working with Darren Cahill.
Mark Philippoussis is returning to Las Vegas to resume his fledgling partnership with Andre Agassi’s former coach Darren Cahill and trainer Gil Reyes, having edged closer to his year-end goal of a return to [...]

Sounds like it in this article in the Sun Herald which has all the hallmarks of someone who has lost his edge.
“I’m not sure what it is,” he said. “I feel comfortable with everything off the court and also when I [am fit and] get on the court, so I guess you put things into [...]