Avilan limited left-handed batters to a .144 (15-for-104) clip and a .219 OBP while posting a 1.52 ERA in 75 appearances last season.
"When he came up, he still has a great fastball and he had a good breaking ball," Braves manager Fredi Gonzalez said of Avilan. "I think sometimes, the situations you get put in, you don't get to develop three pitches, because it's one inning or two hitters.
"You're not going to mess around trying to work on your curveball when you've got second and third and you've got to face Ryan Howard. You go with what your best pitch is, and that's his fastball."
Meanwhile, Shreve hopes to become Atlanta's second bullpen success story out of Mississippi. Shae Simmons, who made his Major League debut on May 31, is 1-0 with a 1.35 ERA and eight holds in 22 appearances.
"Shae Simmons obviously got called up and is doing well. He was dominant the whole year, so I was a little surprised when I got called up," Shreve said.
Shreve will be responsible for facing lefties like Nationals outfielder Bryce Harper, who served as Shreve's catcher at the College of Southern Nevada in 2010. Atlanta went into Saturday with a one-game lead over Washington in the National League East.
The clubs play nine more times this year, giving the friends plenty of opportunities to face off down the stretch if Shreve sticks in the Braves' bullpen.
"I'm close with him," Shreve said. "We work out in the offseason. I'm close with his brother and his family, so it's good. Hopefully I can see him in a little bit."
While Avilan works on adding to his repertoire while aiming to get back on track, Shreve offers Atlanta a fastball, a slider and a changeup. Simmons believes adding life to that fastball helped Shreve overcome a tough 2013.
Shreve had a 4.43 ERA and walked 4.6 batters per nine innings in 42 2/3 innings for Mississippi last season before enjoying a comeback season in 2014, recording a 2.48 ERA and walking only nine batters compared to 76 strikeouts in 54 1/3 innings.
"He was in the upper-80s when we started out in Double-A, and he told everybody, 'I can throw harder,' and he came out and started doing it," Simmons said. "I think it just helped all of his pitches, because the harder you're throwing with the more life you have on the ball, the more revolutions you get on it, so the sharper the spin is and the more movement you create. I think as a whole, he got better just from throwing harder."
Avilan turned 25 on Saturday, and Shreve's bounce-back success story is an indication that Avilan could regain the form that helped him post a 1.69 ERA in his first two Major League seasons. Gonzalez is confident the lefty can improve.
"Go down and get it fixed, get people out and I'm sure we'll see you," Gonzalez said he told Avilan. "I can't give you that date, but I'm sure how things go in the Major Leagues and as relievers go, it's a tough job. We'll get to see him again."