(Over the next week, we will be examining each of the A's free agents to determine which players are most likely to return in 2019.)
After a highly-publicized departure from Washington, Shawn Kelley played a vital role in the A's bullpen the final two months of the season.
The 34-year-old right-hander allowed just four runs and seven hits in 16 2/3 innings, for an ERA of 2.16. He also recorded 18 strikeouts to six walks.
Just as important, Kelley immediately fit in with the rest of the A's clubhouse and really enjoyed his experience in Oakland.
Kelley earned $5.5 million last season in the final year of a three-year, $15 million contract. Last month, he hinted that he was considering retirement.
"(This) may be my last year, I don't know," Kelley told NBC Sports California in September. "I went into this season with no expectations. I'm not playing for another contract. I'm just trying to enjoy this last year and see where life takes me after that."
Why the A's should re-sign him
Kelley emerged as one of Oakland's most reliable relievers in August and September, pitching in just about every type of situation. He also threw a scoreless inning at Yankee Stadium in the American League Wild Card Game.
Oakland's bullpen was one of the biggest strengths of the team, and Kelley was a big part of that. If the A's could talk him into pushing retirement back a year and taking a slight pay cut, he would be worth keeping around another season.
Why the A's should let him go
As effective as Kelley was for Oakland, $5.5 million is a lot for a setup man, especially since the A's have a deep bullpen beyond him. Blake Treinen, Lou Trivino, J.B. Wendelken, and Ryan Buchter should all be back in Oakland, giving manager Bob Melvin plenty of options in close games.
Kelley will turn 35 in April, and it's unclear if he really wants to go through the grind of another major league season. For the A's to bring him back, they would need to be confident that he is fully committed.
It seems unlikely that Kelley will return to the A's in 2019. It would probably take a perfect situation for him to push back retirement, and a pay cut doesn't exactly fit that criteria. After his strong performance down the stretch, he could also receive better offers from other clubs in need of a reliable setup man with extensive big league experience.