The greatest difference between OPS and AVG among qualified batters with an "high OPS" defined by an OPS greater than or equal to the historical average OPS+1 standard deviation (min .878): Carlos Pena 2009 with an AVG of .227 and an OPS of .893 on the back of 39 HR with in ISO of .310. I was accidentally playing with career data at first which showed Joey Gallo posted a career .203 batting average and an OPS of .815 over 347 games. That probably took longer than it should have, but there you go. I have a table of 2200 seasons (14ish percent of all player seasons of qualified batters) but no energy to figure out how to upload it at this point. It's probably searchable on Fangraphs but I have no idea how or if it's possible to sort by multiple stats.