"We thank Rudy, Aaron and Quincy for their time here. They were great professionals and strong community ambassadors of the Raptors," general manager Masai Ujiri said. "The trade gives us good flexibility and more certainty as we plan for our future."
After being traded from Memphis to Toronto last season, Gay -- averaging 19.4 points but shooting a career-worst 38.8 percent -- is the centerpiece of this deal as well.
He's making $17.8 million this season and holds a $19.3 million player option for the 2014-15 season.
By moving Gay, Toronto gains future financial flexibility. Of the four players going to Toronto, only Hayes has a deal that extends beyond this season.
With Gay shipped out, DeMar DeRozan -- scoring a team-high 21.6 per game -- becomes the only Raptor averaging more than 15 points. DeRozan has scored 25.0 per game over his last 10 overall, and put up 29 in each of his last two at home against the Spurs (15-4).
"It ain't the first time for me," DeRozan said of the deal. "A lot of my friends have been traded and moved on. It just gets to a point where you understand it and you know what's going on."
The acquisition of Vasquez, averaging 9.8 points and 5.3 assists, gives the Raptors a solid option behind starting point guard Kyle Lowry (14.8 ppg), while Patterson and Hayes could get an opportunity in the frontcourt.
Amir Johnson made the most of his first start in four games with a career-high 32 points on 14-of-17 shooting to go along with 10 rebounds in Sunday's win. He's made 30 of 42 shots while averaging 23.3 points and 9.0 boards in his last three games.
Lowry had 23 points and eight assists and DeRozan scored 26 for the Raptors, who missed 22 of 26 from 3-point range but ended a 10-game road losing streak to the Lakers.
Now they'll try to take advantage of a San Antonio team that has allowed 107.7 points and a 41.3 3-point percentage in its last three games.
The Spurs have been tough defensively on the road, giving up an average of 91.2 points and holding opponents to 33.9 percent from beyond the arc while winning seven of nine. San Antonio, however, has lost three of five overall following a 13-1 start.
"We give a lot of credit to Indiana," Parker said. "They just played better than us."
Parker and Duncan teamed for 58 points in a 111-106 double-overtime victory in the most recent meeting in Toronto on Nov. 25, 2012. Parker has totaled 66 points and 19 assists in his last two visits to the Air Canada Centre.
San Antonio has won five straight meetings overall.