Batted balls and base on balls. The best bullpens bypass them. In baseball today, relief pitching strikeout rates are at historic highs. The 2018 Milwaukee Brewers (at 10.38) had the highest strikeout per nine innings rate ... in National League history.
The record Milwaukee broke had been set the previous year – Dodgers set the mark in 2017 at 10.24. Of course, those two teams made playoff runs.
Much will be made in the coming days (weeks, months) about the likely signing of lefty Andrew Miller -- and his ability against lefty hitters. But more simply, the Cards' bullpen needs more strikeouts in general – and Andrew Miller, even at his worst, has a high strikeout rate.