A little more than four years after being part of a Draft class headlined by Ian Anderson, Kyle Muller will be coming to Spring Training as a member of the Braves 40-man roster.

Muller, Atlanta's No. 6 prospect per MLB Pipeline, was added to the 40-man roster on Thursday, ahead of Friday’s 6 p.m. ET deadline. This move was made to protect the 6-foot-7 left-hander from being selected during the Rule 5 Draft, which will be conducted on Dec. 10.

The Braves also claimed infielder Jack Mayfield off waivers from the Astros, giving them 38 players on their 40-man roster.

Players first signed at age 18 must be added to 40-man rosters within five seasons or they become eligible to be selected by other organizations through the Rule 5 Draft. Players signed at 19 years or older have to be protected within four seasons. Clubs pay $100,000 to select a player in the Major League phase of the Rule 5 Draft. If that player doesn't stay on the 25-man roster for the full season, he must be offered back to his former team for $50,000.

Players eligible for this year's Rule 5 Draft if they are not on a team's 40-man roster include:

1. Players acquired on the international market in 2016 or earlier
2. High school Draft picks who were 18 or younger as of June 8, 2016
3. College players selected in the MLB Draft in 2017 or earlier

Muller has been an intriguing prospect since the Braves took him with the 44th overall selection in the 2016 MLB Draft. The club used its first two picks that year on Anderson, who was one of this year’s top rookies, and Joey Wentz, who was traded to the Tigers in the ‘19 Trade Deadline deal that brought Shane Greene to Atlanta.

Muller started to show promise during the 2018 season, and then truly started opening eyes while posting a 3.14 ERA over 22 starts for Double-A Mississippi in ‘19.

Whether he ends up being a starter or reliever, Muller’s rise toward the Majors will be determined by his command, which was an issue when he made a couple appearances in Grapefruit League games this past spring. He issued 5.5 walks per nine innings with Mississippi in 2019.

The Braves’ No. 24 prospect, left-hander Thomas Burrows, was not protected from the Rule 5 Draft.

Mayfield, a 30-year-old utility infielder, had a .481 OPS over 112 plate appearances with the Astros spread over the past two seasons, playing mostly shortstop. He has a .791 career OPS in the Minors, including a .916 mark in 100 games with Triple-A Round Rock in 2019.