Doesn't this sentence describe 99% of MLB hitters? And not that this disproves or proves your theory, but a quick glance at that link above shows that Dunn has moderate to amazing success against quality pitchers like Clemens, Wood, Lieber, Prior, and Clement. Though Ben Sheets has absolutely owned him...yikes! Obviously that's not scientific, but I think it shows that it's very possible that Dunn is at least league average against quality pitchers, especially when compared to all the other hitters in baseball.