SEATTLE -- Looking to add some pitching depth for September after trading away a trio of right-handers in the past week, the Mariners claimed right-hander Walker Lockett off waivers from the Mets on Tuesday and activated Kendall Graveman off the 10-day injured list.

Graveman has been a starter his entire career and was the A’s Opening Day starter in both 2017 and ‘18, but the right-hander will be given a chance to pitch out of the bullpen now after dealing with neck issues since his second start with Seattle on Aug. 2.

Graveman has a benign tumor on his spine and was told by doctors the situation won’t get worse if he pitches, but it causes difficulties when he gets tired after longer stints. The 29-year-old has been throwing at the Mariners’ alternate training site in recent weeks and now will get a shot at a new role in Seattle’s depleted bullpen.

Outfielder Braden Bishop was optioned to the alternate training site to open a roster spot for Graveman, who signed with Seattle this season on a one-year, $2 million deal after spending the past two years recovering from Tommy John surgery.

The Mariners also added Lockett, a 26-year-old who is out of Minor League options and was designated for assignment by the Mets last Friday after pitching two scoreless innings of relief and getting the win in a 6-4 decision over the Yankees.

Lockett pitched two games for the Mets this season, allowing seven hits and five runs over six innings in a start against the Phillies on Aug. 14, and he was 1-1 with a 5.63 ERA with eight strikeouts in eight innings overall.

The Mariners traded starting pitcher Taijuan Walker to the Blue Jays last Thursday and dealt relievers Dan Altavilla and Taylor Williams to the Padres over the weekend, along with injured reliever Austin Adams. While the Mariners’ rotation is full at the moment, with rookie Ljay Newsome taking Walker’s spot, the bullpen has taken serious hits, with eight relievers on the injured list and now Altavilla and Williams departing via trades.

Lockett opened the season on the 10-day IL with discomfort in his lower back before being activated for his lone start of the year. He’s gone more to a 93-mph sinker this season, but also relies heavily on a changeup, cutter and curveball mix.

A fourth-round Draft pick of the Padres in 2012, he made his MLB debut with San Diego in 2018 when he pitched in four games, including three starts, going 0-3 with a 9.60 ERA. The 6-foot-5, 225-pounder was traded to the Mets in January 2019 along with current Mariners utility man Sam Haggerty for catcher Kevin Plawecki and went 2-1 with a 7.63 ERA in 11 appearances (five starts) in his two seasons with New York.

Lockett has been primarily a starter throughout his career, and was 3-3 with a 3.66 ERA in 11 outings (10 starts) for Triple-A Syracuse in 2019.

• The Mariners and Blue Jays have announced that the player coming to Seattle from last Thursday’s trade of Walker to Toronto will be Minor League outfielder Alberto Rodriguez. The 19-year-old from the Dominican Republic hit .301/.364/.422 with two homers and 13 stolen bases in 47 games in the Gulf Coast Rookie League last year.

• Infielder Ty France and catcher Luis Torrens, two of the four players acquired from the Padres in the seven-player trade on Sunday, were activated and added to the 28-man roster on Tuesday after passing their COVID-19 intake testing. Both will be available when the Mariners resume action on Friday against the Rangers in Seattle. Outfield prospect Taylor Trammel will report to the alternate training site in Tacoma, while reliever Andres Muñoz is rehabbing from Tommy John surgery and won’t pitch until next year.

Catcher Joe Hudson and infielder Donovan Walton were optioned to the alternate training site to open spots for the additions. The 28-man Major League roster is at 27, which presumably leaves a spot for Lockett to be added as well once he clears intake testing.

• Right-handed reliever Zac Grotz had his contract outrighted to Triple-A Tacoma, which puts the current 40-man roster at 35 players and also opens a spot at the alternate training site.