For the price they paid, though, this is an excellent signing. 
With that in mind, it’s hard to know where Treinen ends up slotting for the Dodgers next year. He could form an outstanding 8-9 back-end duo with Kenley Jansen, take over as closer (Jansen has started to decline, after all), serve alongside Joe Kelly and Pedro Baez in setup capacity or pitch in lower-leverage situations. We’ll have to see which version of Treinen the Dodgers get. 
In 2018, Treinen was 9-2 with 38 saves in 43 chances. He pitched to a 0.78 ERA and 0.83 WHIP with 100 strikeouts against 18 unintentional walks in 80 1/3 innings. Given his ability to work multiple innings — he went at least two innings 10 times and more than one inning 19 times — there was an argument that he was the best reliever in baseball. 
For the Dodgers, this is an upside play and they can obviously spare the million to find out if Treinen can re-capture the 2018 magic.  The Dodgers have agreed to a one-year, million deal with reliever Blake Treinen, reports Jeff Passan of ESPN. Treinen, 31, was a bit of a surprise free agent after the A’s non-tendered him last month. A year ago, such a move would’ve been unthinkable, but he took a big step backward in 2019 and the A’s were looking to shed payroll. 
As noted, 2019 was a different story. Treinen lost his closer job and ended up with a 4.91 ERA and 1.62 WHIP. 
It’s fair to say Treinen is hit or miss. He was mediocre in 2015, very good in 2016, terrible with the Nationals in 2017, great with the A’s after being traded in 2017, upper-level elite in 2018 and sub-par in 2019. That kind of checks every performance box, no?