I haven't played in a minute but I used to do pauper 5c tron in mtgo leagues years ago, the meta is so much faster now and there have been a couple of bans that have hurt it. Prismatic Prism and Bonder's Ornament are gone. Tolarian terror decks can have a 5/5 out very early and tron decks are just too slow to keep up. Lots of artifact hate going around. Red decks apparently main Cleansing Wildfire these days...many such cases. I am told some mono green variants can still do some stuff but tron is definitely falling off.