I don't know why this never occurred to me before really, or why at age 60 it HAS occurred to me as if I have nothing else to think about. Whatever.
So, doing a quick calculation, from 1915-1917 at ages 19-21, Babe Ruth was part of the regular Boston rotation, starting 28 (and appearing in 31) games in 1915, 44 in 1916, and starting 38 and pitching in 41 in 1917. In those three seasons, combined, he had a total of 395 plate appearances, and hit 9 home runs, while hitting .315, .272, and .325 respectively. In other words, he was already a young Babe Ruth, in the sense that we can extrapolate a like 6 more homers if we were to add 200 PA and make it the equivalent of a single season - he hit 4 homers at age 19 in 1915 in 103 plate appearances and 92 AB, which is one for every 23 ABs.
The following year he started 20 games as a pitcher and had 380 PA. and he hit 11 homers. If we add 200 PA and 5 more homers it is a 16 home run season. If we take the first extrapolation - I admit that these are merely counter-factuals - and figure 15 homers a year had he played OF full-time 1915-1917, and 16 for 1918 on that same assumption, then whereas Ruth hit 20 homers over those four seasons playing mainly as a pitcher, he might have reasonably be assumed to have hit a total of 61 instead, or 41 more, which would have given him, strangely, 755, Henry Aaron's total. Henry would have played another game in that case of course, and hit one more.