Not to weigh in particularly on either side, but a confounding factor in discussing OBP versus SLG is that they aren't on the same scale. By definition, the maximum OBP is 1.000 while for SLG it's 4.000. While batters routinely reach a larger fraction of the maximum of OBP than for SLG, it's still the case that the league leader in OBP will be ahead of the league average by fewer points than the leader of SLG is. This year Mike Trout leads the majors in OBP with .152 more than MLB average, while for SLG it's Trout (again) by .282 more than the average. You can't just compare the two stats directly. It's a bit like comparing Celsius and Fahrenheit, except that those two scales are measuring the same actual thing. For me it means that .010 of additional OBP is more valuable than .010 more SLG. If someone's regression study doesn't attempt to correct for scale, then the conclusion will be that getting on base is more important than hitting for power. And I'm not sure that it's answering the actual question, done that way. This difference of scale has always been one of the prime criticisms of OPS. You're adding a pound of apples to a dozen oranges. As an aside, by sheer coincidence, yesterday I ran across a reference to a precursor to OPS, in which OBP plus SLG plus BA were added together. The guy called it ''combined triple average." I kind of like it. It over-weights batting average, but that means the criticism of OPS that it gives too much weight to walks is mitigated, likewise the outsize effect of a few extra wallops over the fence. If it overweights base hits, well, that's IMO the single most valuable skill in the sport, so it's not a major sin - but like OPS the combined triple average is better than BA alone. http://archive.boston.com/news/globe/living/articles/2005/06/23/his_numbers_are_in_the_ballpark/