Possible Jayce bug

In a recent game, our Jayce started the game saying he would do outrageous damage because of a bug with an item. While he fed in lane, he got about 14 kills once he got his items. It seemed fishy to me since his performance was otherwise so poor. http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2266577836/36886623?tab=overview This was the game. I suspect the item would be Black Cleaver. Thought I'd mention it in case something weird was going on.