I’m going to preface this by saying that “fire the hitting coach” is often the easy way out. Hitting coaches generally get too much blame when things go wrong, and not enough credit when they go right.
But the change in Cubs batting coaches from John Mallee to Chili Davis appears to have made the ballclub markedly worse offensively.
Davis was a fine hitter as a player. In 19 big-league seasons he hit .274/.360/.451 with 2,380 hits and 350 home runs. That produced 38.2 career bWAR. He was the Oakland Athletics hitting coach from 2012-14 and Boston Red Sox hitting coach from 2015-17.