I'd go with equal.

Now this doesn't mean take pitchers OPS of .740 and ave. it with hitters OPS of .840 to get a .790 OPS average.

What it means is this pitcher vs. an ave. hitter should produce a .740 OPS. Thus if the ave league wide hitter was .770 OPS than a guy .070 OPS higher will bump that pitchers .740 OPS to .810 OPS if that pitcher faced that batter 2000 times.

The same must be looked at for the hitter in comparison to what league wide ave. was as well. If the ave. pitcher was .780, then that pitcher is .040 OPS better than ave, thus the hitter would have a .800 OPS over 2000 AB's.

The difference in ave OPS would be due to either NL or AL, which throws a wrench into the whole thing as NL pitchers face other pitchers, thus a lower ave. OPS.

Throw in lefty/righty splits, defense(specifically DP's), DH or no DH, batting lineups, etc., many additional factors come into play.