After graduating from Alhambra High School,[1] Ramirez enrolled at California State University, Fullerton.

[3] After the season, the Boston Red Sox selected Ramirez in the fourth round (142nd overall) of the 2011 Major League Baseball draft.

[5] He also led the league's relievers in innings pitched (67+1⁄3), finished third in saves, and not allowed a home run in 42 games.

[6] From 2012 through 2014, Ramirez posted a 7–10 record with a 2.93 ERA and 24 saves in 95 games, including a 1.15 WHIP and a 4.00 K/BB ratio (216-to-54) in 230.0 innings of work.

[3] Ramirez earned a promotion to the Boston Red Sox on July 3, 2015, and made his major league debut on the same day, throwing one inning of relief against the Houston Astros at Fenway Park.

[9] The following season, Ramirez was a permanent member of the Angels bullpen, appearing in 69 games, with a 4.54 ERA.

On December 7, 2020, Ramirez and a player to be named later were traded to the Cincinnati Reds in exchange for Raisel Iglesias.

[19] Ramirez made 36 appearances for the Diamondbacks in 2021, recording a 2.76 ERA with 29 strikeouts across 32+2⁄3 innings pitched.

He features a deceptive delivery from a low three-quarters arm slot and hides the ball well until the point of release, making him especially tough for right-handed hitters to pick up his 89-92 mph fastball, and is considerably effective at getting left-handed hitters out with his solid 82-84 mph changeup, which he can throw in any count and uses it to keep all batters off-balance.