Leake, who can be a free agent after the season, was 9-5 with a 3.56 ERA in 21 starts but has saved some of his best numbers for the end of his tenure with the Reds. The 27-year-old was 4-0 with 0.60 ERA over his last four starts, including eight scoreless innings vs. the Cardinals on Tuesday.
"The fact I've been able to learn over the last few outings is what I enjoy the most," Leake said after Tuesday's start, seeming resigned to be being moved. "It's been a long six years so far. It's just a matter of continuing to get better. These last few starts, I've learned a lot."
The Reds made Leake their first-round selection in the 2009 Draft, and he went straight from college to the Major Leagues when he debuted in 2010. Lifetime in his six seasons, he went 62-47 with 3.87 ERA in 168 games for Cincinnati, including 163 starts.
Leake gives the Giants another legitimate starter in a rotation that already includes Madison Bumgarner, Matt Cain, Jake Peavy and Tim Hudson.
Mella, 21, is 5-3 with a 3.31 ERA in 16 starts this season for Class A Advanced San Jose and was at Great American Ball Park earlier this month for the SiriusXM All-Star Futures Game. In four seasons since being signed in 2011, he is 15-12 with a 3.01 ERA over 58 games (57 starts) with 282 strikeouts over 272 1/3 innings.
Ranked the No. 25 prospect in the Giants' system, Duvall played 28 games in the big leagues for the Giants in 2014 and batted .192 with three home runs.
At Triple-A Sacramento this season, Duvall batted .279 with 26 homers, 79 RBIs and 25 doubles in 99 games. The 26-year-old, a Kentucky native, played for the University of Louisville and was an 11th-round Draft pick for the Giants in 2010.
Even with three-straight victories, the Reds are eight games under .500 with a 46-54 record that has them in fourth place in the National League Central and 9 1/2 back for the second Wild Card spot. That has made them sellers before the 4 p.m. ET Deadline today.
Besides Leake and Johnny Cueto, who was traded on Sunday to the Royals for three left-handed pitching prospects, the Reds could also wind up moving more players. Right fielder Jay Bruce and closer Aroldis Chapman have been frequent rumor topics in recent days. Following Thursday's 15-5 win over the Pirates, but before the Leake deal was announced, Reds manager Bryan Price was asked if he would feel relieved once the Deadline passed.
"I think everyone will be," Price said. "I think that we all talk about the names that are out there. There's always things that happen that are a surprise. I don't think there is probably a lot of guys that are comfortable and are able to sit in front of their locker and not think about the Trade Deadline. When we get past it, I think we'll be in a better place there.
"That being said, of course, we've won three in a row with the Trade Deadline hanging over our head. I've been really impressed with how the guys have handled it. They've done a really nice job under some tougher circumstances here."