On Alvarado it was more about the freshness than the left-handedness. Remember we chose a postseason bullpen with 8 pitchers in it including 4 left-handed pitchers. The RHPs all got used, 2 of them (Kerkering and Hoffman) twice. Allard and Alvarado were unused left-handers and Alvarado is actually good. Strahm also got overused a bit (back to back versus a fresh Alvarado).
I know the playoffs are often about riding a hot hand pitching-wise, but it really looks like we used several tired relievers coming off poor games instead of a fresh Alvarado.
Alvarado's August was bad: 9.2 IP, 10 H, 5 ER, 8 BB, 7 K
His September was just fine though: 9.1 IP, 5 H, 3 ER, 3 BB, 11 K
I know September was lower leverage, but really it is not as if we should be trying to hide Alvarado like we should have been trying to hide Kimbrel last year. Thomson seems like he is over-correcting here unless there is something else going on with Alvarado (remembering the off field issues that gave him a brief trip home).
Note also that Kerkering had a 5.59 ERA this season on zero days rest. And last year he almost never did that until the playoffs and then was bad in the playoffs.