that's the point, relievers aren't consistent either on an individual level or as a group. If you think that it's definitely the best, then you're saying relievers are predictable

Mediocre relievers aren't consistent. The best relievers ARE consistent. And now they have THREE of the best relievers in the game (three of the top, what, 5-6?). I don't know what's hard to understand. Maybe their ERAs vary a little bit because 1 additional bad outing per year can make a big different in so few innings, but for the most part the top relievers in the game are shut-down guys for many years at a time.

Kimbrel has had 5 straight years with ERAs between 1.01 and 2.58

Chapman 4 straight years between 1.51 and 2.54

Jansen 5 straight years between 1.88 and 2.85

Uehara 4 straight years between 1.09 and 2.52

Papelbon 9 of 10 years beween 0.92 and 2.94