SEATTLE -- The Mariners added a veteran arm to their bullpen Thursday, agreeing to a one-year, $1.6 million contract with Yoshihisa Hirano.

Hirano has spent the past two seasons with the Arizona Diamondbacks, appearing in 137 games with a 3.47 ERA. Hirano was very good in 2018, when he struck out 69 batters in 66 1/3 innings and allowed just 18 earned runs. He struggled last season while appearing in 62 games. He had a 4.75 ERA and issued 22 walks in 53 innings.

Before joining the Diamondbacks, the 35-year-old Hirano spent 11 seasons pitching in Japan for Orix of the Pacific League.

"We believe his combination of experience and bat-missing ability brings needed stability to our bullpen," Mariners GM Jerry Dipoto said in a statement.

Hirano can earn $500,000 in bonuses based on pitching appearances: $50,000 each for 30 and 35, $75,000 apiece for 45 and 50, $100,000 for 55 and $150,000 for 60.

He also can get $450,000 in bonuses for games finished: $50,000 for 20, $75,000 apiece for 25 and 30, $100,000 for 35 and $150,000 for 40.

Hirano would receive a $250,000 assignment bonus each time he is traded but not if he is claimed on waivers, the money payable by the new team. Hirano cannot be sent to the minor leagues without his consent.

He will become a free agent when the contract expires.

Left-hander Ricardo Sanchez was designated for assignment to clear a spot on the 40-man roster. Sanchez spent last season at Double-A Arkansas.