There's OPS+, ERA+, even wRC+. Is there home run plus (HR+)?
In fact why isn't there a plus for most baseball stats? Plus compares an individual's average to the league and factors ball park differences.
Of course, we baseball fans will need to stop evaluating home run data simply on totals and start using averages, like home runs per at bat. We embraced batting average over a century ago. Since the advent of modern home run hitting in 1920 you'd think we'd have done the same for homers.
We know the Babe hit 60 and Bonds 73 but that doesn't enable us to have a quick way to compare them.