With no runners on batters are hitting .808 OPS (.275 AVG) and with men on it's .631 OPS (.210 AVG). There's about a seasons' worth of PA's in each scenario, so could still be luck, or maybe's he's just better in the stretch? He's definitely a competitor though.
We'd need more data i think, like batted ball data.
RISP guys hitting .156 off him. Usually pitchers get worse with men on due to infield placement changes.