Yacabonis fired a clean ninth inning in a loss to the Giants in his Mariners debut Wednesday.
The 28-year-old had his contract selected earlier in the day after spending the first three weeks of his tenure with the organization at the alternate training site in Tacoma. Yacabonis doesn't exactly arrive with an encouraging career arc in tow, as he's seen his ERA balloon from a 4.35 figure during his 2017 rookie season in Baltimore to 6.80 in 2019. He'll likely be deployed in low-leverage scenarios such as Wednesday's for what remains of the regular season.