The hard-throwing Middleton had a very promising rookie season in the Angels bullpen in 2017, though he was limited to only 25 1/3 total innings in 2018-19 due to Tommy John surgery. This past season, Middleton threw 12 innings over 13 appearances for Los Angeles, posting a 5.25 ERA, 1.83 K/BB rate, and 8.3 K/9.
According to Statcast, Middleton has consistently delivered very good fastball spin rates over his career, and his advanced metrics indicated that he was somewhat unlucky to post such a high ERA in 2020. Nonetheless, the Angels non-tendered Middleton on December 2 rather than pay a projected arbitration salary of roughly $1MM.
Seattle GM Jerry Dipoto was the Angels’ general manager when Middleton was drafted by the Halos back in 2013, and the two will now reunite on what Middleton described as his “home team” (he hails from Portland, Oregon) in the Mariners’ press release. Even with the guaranteed salary of a MLB deal, the Mariners are taking what is likely a low-cost flier to see if Middleton can regain his rookie form now that he is healthy, and under somewhat more normal circumstances than the unusual 2020 season.
More analysis to come…