I think its pretty obvious there is large disparity between how Rizzo views Finnegan and how a lot of MLB does.
Rizzo views Finnegan as an all star closer with a mid-3s ERA, has a solid WHIP, and who consistently posts and pitches. The problem is that he views that as an excellent closerr/high leverage reliever. Borderline elite.
But Finnegan's metrics tell different performance expectations. He usually outperforms his FIP and xERA, but this season is the largest disparity of his career. His ERA is 3.48, but his FIP and xERA are over a run higher (4.75/4.78). That is the largest disparity of his career.
Deeper than that, while his WHIP is 1.09, this seems to be more indicative of luck. While hitters are hitting .206 off him, he has an xBA of .272. He is in the 25th percentile of barrel rate, first percentile of hard hit rate , and 2nd percentile in exit velo. In other words, when hitters hit the ball, they hit it.
Now, thats not exactly the worst thing. Lot of high leverage relievers throw hard and, as a result, give up a lot of hard contact. But they usually make up for it by striking guys out. But Finnegan is kind of well ... average. He has a 9 K/9. Thats fine, but its not elite high leverage fine. He is in the 41 st percentile in chase and 39th in whiff. While does sit in the 65th percentile in strikeouts, it seems to be the result of a lot of batters getting caught looking. While a strikeout is a strikeout, low chase and whiff numbers are usually indicative of a lesser quality of "stuff"
Truth is, if Derek Law had been the closer, he'd probably have better traditional stats than Finnegan.
Finnegan's meltdown probably just reinforced the mindset that, on a playoff caliber bullpen, Finnegan is just a decent middle relief option.