A relative unknown in the Chicago Cubs system coming into the season, first baseman Matt Mervis arguably had the best season on the farm. Matt Mervis wasn’t supposed to be much of anything. Mervis was an undrafted free agent following the 2020 MLB draft and the first baseman entered the season with Chicago Cubs affiliate High-A South Bend on nobody’s radar, but that changed quickly. The Duke product tore through High-A, slashing a ridiculous .350/.389/.650 with seven home runs in 27 games and earning a promotion to Double-A. Still, with a strikeout percentage of nearly 25% and a walk percentage…