"I didn't want to finish my career in the States like this, but unfortunately it looks like my time is up and now it's onto something else," Lyle wrote.
When Lyle returned to the Tour in October 2014 after his second bout with leukemia, the Aussie was equipped with 20 starts with which to earn $283,825. While Lyle made the cut in each of his first two starts back, he missed 13 of his next 15 cuts and returned home to Australia "shattered" after a second-round 79 at the Puerto Rico Open in March.
While he played the weekend in his competitive return to the Tour, finishing T-62 at the Barbasol Championship in July, missed cuts at the John Deere Classic and in Greensboro left him well short of the earnings requirement tied to his medical extension.
"After having so much time away from professional golf, it was incredibly hard to regain my 'match fitness' and be able to string together four good rounds of golf," he wrote. "My medical status also meant that I was a long way down on the list of players, so I was only able to play certain events and often had several weeks off in between. Most pro golfers would agree that you usually need to keep playing to get some consistency and improve on the week before, but that was not something I was able to do."
Lyle is exempt into the second stage of Web.com Tour Q-School, but with his oldest daughter set to begin kindergarten he plans instead to return to Australia, still with an eye on playing a few tournaments there this fall.
"They have given up a lot by following me around the world to help me resurrect my dreams, I think now it's my turn to give a little back to them and let them follow their dreams," he wrote.
Lyle, 35, also entertained the notion of pursuing a career in golf commentary in the near future, but he reiterated that he's not yet ready to retire from playing competitively.
"The fire is still there and I still feel like I can win tournaments. I want to be a golfer," he wrote. "Tournament golf has been a huge part of my life as both an amateur and a professional, so I'm not completely ready to part ways with it."