I am not arguing who is going to be the better player this year. Simply pointing out that in just about EVERY statistical category last season, both out of conference and most importantly in conference play when the competition got MUCH tougher, Mathis put up "bigger" numbers than Harper.
https://s3.amazonaws.com/sidearm.sites/scarletknights.com/documents/2018/11/9/MBBSeasonStats.pdf
https://scarletknights.com/documents/2019/1/15/b1gonlystats.pdf
Harper was by far the more efficient player though.