Mariners general manager Jerry Dipoto continues adding experienced late-inning relievers to his bullpen as the club announced the signing of free-agent right-hander Keynan Middleton on Wednesday.

One day after acquiring Rangers closer Rafael Montero via trade, Dipoto signed Middleton to a one-year Major League deal. Outfielder Phillip Ervin was designated for assignment to open a spot on the 40-man roster for Middleton.

Middleton was a third-round Draft pick of the Angels in 2013 when Dipoto was the GM in Anaheim. The 27-year-old from Portland, Ore., had a strong rookie campaign with the Halos in '17 -- going 6-1 with a 3.86 ERA and three saves in 64 appearances -- and opened the ’18 season as the team’s closer, compiling six saves and a 2.04 ERA in 16 games before right elbow issues led to Tommy John surgery.

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Middleton returned in September 2019 and put up a 1.17 ERA in 11 outings, then had a 5.25 ERA in 13 appearances during the pandemic-shortened ’20 season before being non-tendered on Dec. 2.

But Middleton’s fastball velocity jumped from an average of 94.1 mph in 2019 to 97.1 this past year, per Statcast, and the Mariners could have another closing candidate if he remains healthy.

For Middleton, signing with Seattle proved to be an easy decision, as he saw a young club with plenty of opportunity and a chance to return to the Pacific Northwest.

“Since I heard the Mariners were interested, I just knew this was a no-brainer for me,” Middleton said. “My family is so close, my daughters live down in Portland, so this is everything I wanted with an organization that is trending in the right direction. I’m really happy to be a part of it.”

The Mariners have now added Montero and Middleton -- as well as re-signed Kendall Graveman -- to a young bullpen that returns promising rookies Yohan Ramirez, Joey Gerber and Anthony Misiewicz.

Middleton grew up in Oregon and attended Milwaukie High School and Lane Community College before being drafted by the Angels. He spent his first three years in the Minors as a starter but moved up quickly when he converted to the bullpen. He made his MLB debut in 2017, and his 64 appearances that year were the third-most by an Angels rookie. He also led American League rookies that season with an average fastball velocity of 97.2 mph.

The 6-foot-3, 205-pound pitcher played football, basketball and baseball in high school and had still been more focused on basketball at Lane CC when the Angels drafted him. He credits Dipoto with seeing more in his baseball future than he saw himself and is happy to be reunited with his former GM in Seattle.

“I trust Jerry 100 percent because it ended up working out for me,” Middleton said. “They drafted me as a freshman out of Lane when basketball was honestly my No. 1 sport. It was a shock when they drafted me. I was not ready to play pro ball. I had to take my lumps and learn how to pitch and play the game. But I never was discouraged, and when Jerry was in the organization, he never let me get discouraged.”

Middleton took some more lumps last year when he struggled with the command of his pitches and couldn’t replicate the September success of the 2019 season.

“I just had a rough season,” he said. “It was the first rough one I’ve had and I’m just looking to move past it. I’m going to learn from my mistakes and be better. When I came back and finished the season in 2019, I felt really good and crisp, but the [velocity] wasn’t there. Last year, the velo was there and at times I was just trying to overthrow or trying to throw fastballs past guys because I felt so good. I learned from my mistakes and I’m going to move forward.”

Middleton felt he leaned too heavily on his fastball last year as he threw it on 59 percent of his pitches. He also features an 88 mph changeup and an 87 mph slider and believes he’ll need to incorporate those more in the future. In his four seasons in the Majors, he has struck out 96 batters and walked 40 in 95 2/3 innings while posting a 3.48 ERA.