After a big trade for Sonny Gray , the next NL Central righty the Red Sox have added might seem considerably less interesting, given that new addition Johan Oviedo has spent most of five seasons for St. Louis and Pittsburgh being decidedly unremarkable. You wouldn’t look at a career 4.24 ERA and a 4.61 FIP -- to say nothing of a 15-26 record -- and find much to be excited about.

That may be true, and yet we also have learned endlessly that teams aren’t just looking at ERA or win/loss record to try to find value; this is why Dylan Cease got valued, and so did Devin Williams , and really so did Gray, all despite ERAs in the 4s last year. It’s because ERA isn’t a terribly predictive metric, not more so than some of the fancier advanced models, and even not more so than something as sim

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