I think Gvodzyk wins a decision. He beat a Stevenson who came to the fight with a better gas tank than the Stevenson that Jack fought. He also showed that he was a go getter, while Jack showed that a gassed opponent could still paralyze his solar plexis with body shots.
Jack's a fighter that has surpassed expectations but I don't think at LHW he poses a significant threat to the top boys. OG is better in every department.