The 31-year-old declined an $8.8 million player option with the Spurs to become an unrestricted free agent this summer.
Last season was Gay's first with San Antonio. He averaged 11.5 points and 5.1 rebounds per game, which were his lowest marks since his rookie year in 2006-07.
The wing also came off the bench for most of the year, starting only six of 57 games. This was a major change for a player who had started all but three games from 2007 to 2016, splitting time between the Memphis Grizzlies, Toronto Raptors and Sacramento Kings, averaging 19.3 points per game in this stretch.
However, his role was much more limited last season, playing a career-low 21.6 minutes per game.
Despite his disappointing season, he seemed to appreciate what the Spurs provide.
"It's like no other organization in the league," he said in May, per Alex Kennedy of HoopsHype. "They are definitely family-oriented—there's a family atmosphere and family is everything. On the court, it's very different. It's the epitome of team basketball. Everyone is playing for each other, and it's always been that way."
This likely caused him to remain with the team despite initially opting out in June.
Injuries have been a problem for Gay, who has only played 87 games the last two seasons, but the Spurs need offense after ranking just 27th in the NBA in points per game in 2017-18.
Even if he isn't the scorer he once was, the 6'8" forward can be a valuable role player who can provide instant offense when given a chance.