My original statement was not presented as fact (thus the "or at the very least, a much easier to measure" parenthetical aside). And even once someone is hired to replace Coles, and the entire 2019 season has been played & the stats are final, it will be impossible to tell if our holdovers from 2018 performed better or worse because of a change in skill level, regression to the mean, coaching, luck, injury, issues in their personal life, or any of a number of factors that could possibly contribute. Conversely, if we trade for Whit Merrifield (or Hiura gets called up & rakes) it will be a lot easier to tell why our 2B wRC+ went from 78 in 2018 to 115 (hypothetically) in 2019.