Rob Brantly's journey in Major League Baseball began when he was drafted by the Detroit Tigers in the third round of the 2010 MLB Draft. A catcher by trade, Brantly quickly demonstrated his potential in the minor leagues, which led to his MLB debut with the Miami Marlins in 2012. During his rookie season, he played in 31 games, hitting .290 with three home runs and eight RBIs, showing promise as a young player.

In 2013, Brantly took on a more significant role with the Marlins, appearing in 67 games. However, his batting average dipped to .211, and he struggled to find consistency at the plate. Despite these challenges, he continued to develop his skills behind the plate, gaining valuable experience in handling a pitching staff and improving his defensive capabilities.

The following years saw Brantly moving between teams and spending time in both the major and minor leagues. In 2014, he was claimed off waivers by the Chicago White Sox, where he played sparingly over the next two seasons. His time with the White Sox was marked by limited opportunities at the major league level, as he spent much of his tenure with their Triple-A affiliate, the Charlotte Knights.

Brantly's career took another turn in 2016 when he signed a minor league contract with the Seattle Mariners. Although he did not make an appearance for the Mariners in the majors, he continued to hone his craft in the minors. The following year, he joined the Cincinnati Reds organization, where he briefly returned to the majors, playing in 14 games during the 2017 season.

In 2018, Brantly signed with the Atlanta Braves, though he did not see major league action with the team. Instead, he spent the season with their Triple-A affiliate, the Gwinnett Stripers. His perseverance paid off in 2019 when he signed with the Philadelphia Phillies and made a brief appearance in the majors, playing in one game.

The San Francisco Giants became Brantly's next destination in 2020. During the pandemic-shortened season, he appeared in one game for the Giants. Despite limited playing time, he continued to be a reliable presence in the minors, offering depth and experience to the organizations he joined.

In 2021, Brantly signed with the New York Yankees, where he once again found himself splitting time between the majors and minors. He played in six games for the Yankees, providing veteran leadership and serving as a backup catcher.