Editor's note: Over the next two weeks, we will examine 10 A's players who may or may not return to Oakland next season. For each player, we will provide reasons why the A's should bring him back and reasons why they should not, followed by a final determination.

Blake Treinen, RHP

Contract: Final year of arbitration (projected to get $7.8 million after earning $6.4 million this season)

Reasons to bring him back

In 2018, Blake Treinen enjoyed one of the greatest seasons in MLB history. The right-hander went 9-2 with 38 saves and a 0.78 ERA, notching 100 strikeouts in 80 1/3 innings.

Unfortunately, Treinen followed that up with the worst season of his career, going 6-5 with a 4.91 ERA in 2019, ultimately losing the closer job to Liam Hendriks. Still, Treinen's stuff looked dominant at times and he could certainly bounce back in 2020.

Treinen is still just 31 years old and should have some productive years ahead of him. His fastball averaged 97 mph this season with explosive movement. If he can improve his command, Treinen could still be a productive reliever moving forward.

Reasons to let him go

Treinen is coming off an incredibly disappointing season. He entered the year as one of the top closers in baseball, but quickly lost his closer job due to injury and poor performance.

Treinen's 4.91 ERA, 1.62 WHIP, and 5.14 FIP were all career worsts, as were his 37 walks in just 58 2/3 innings. He saw his season come to a premature end when an MRI revealed a stress reaction in his back. And pitchers and back injuries don't mix well (see: Marco Estrada). Tendering Treinen a contract would be a major risk.


Final verdict

Treinen could very well return to being an effective relief pitcher, but the A's can't afford to take that chance for nearly $8 million. That money would be better spent on multiple relievers to help shore up the team's shaky bullpen.

[RELATED: A's stay or go candidate for 2020 season: Jake Diekman]

Between Treinen's on-field struggles and the injury concerns, Oakland would be better off seeking an offseason trade of its former All-Star closer. If the A's can't get a deal done, look for a non-tender.