the problem here is that you're talking about year-to-year flukes. greene has been way, way better away than at home every year since he started playing in san diego. he's had about 1100 PAs home and away, and the difference in OPS is 200 points. put it this way. todd helton's home OPS is 1.128 over the course of his career, and his road OPS is .885. If you played for an offense-neutral park and were to trade for him during a year where he is pretty much at his career averages, wouldn't you expect his OPS to be closer to .885 than to 1.128? Now everyone would say "of course, but that's because Todd Helton plays at a mile above sea level," but the past 2-3 years, San Diego has been as much of a pitcher's park as Colorado has been a hitter's park. Earlier in Helton's career, Colorado was a more extreme park toward hitters than San Diego is toward pitchers, but the fact remains that San Diego is the best pitcher's park in baseball, by a pretty significant margin. Add to that the fact that Greene's game - fly balls and hitting for power - is affected very adversely by the heavy marine air and deep outfield of Petco. So if you're trading for Khalil Green, I think you can have a pretty high level of confidence that he'll be at or very slightly below his career road OPS, rather than near his overall career OPS.