As some astute coaches have pointed out, Cogs actually has a history of being ordinary and then punching out big scores.
In 2018, on his way to a 21/108 season after starting with 5 straight 100s he had 10 games out of 16 at 100 or less. Four of his 100+ scores in that time were 157, 150, 143 and 138.
In 2016, on his way to a 21/106 season he again punched out 6 straight 100s and then had 6 of 13 at 100 or less while still hitting 139, 138 and 121 in that run.
GC have given up some huge scores so may just have accentuated one of his spike games. He looks to be a player that either goes on a 5-6 game run of solid hundreds or pumps out 70-90 type scores with the occasional spike. His spikes seems to be getting bigger (154 and 207 this year) but he's already had a run of 4 100+ scores so I'd say settle in for a roller coaster: frustrating 80s and 90s punctuated with 140+.