My point is not that this isn't a must-win game. I think that Seranthony is just as or more important than Eflin to the bullpen. Remember we have seen Eflin like 5 times in the bullpen so its not as if he has a great track record. He throws strikes, but is also pretty hittable. Seranthony is a better strikeout pitcher and the sample of his bad outings is also very small.
Reading way too much into small samples of performance is as bad as keeping people in set roles. Thomson seems very open-minded in his bullpen usage. We don't know at all that Seranthony had a bad bullpen. He probably was going with the hot hand in Eflin, but if he needed a strikeout maybe he would still have gone with Seranthony. I don't want to sit Alvarado either after he made one bad pitch.
Getting the most out of all of our top arms is what we should want.