Some quick numbers to illustrate the point:
The Braves have scored a total of 344 runs on 218 HRs. That means they hit a HR with 0.58 runners on base, on average.
Acuna has hit 36 HRs: 23 with 0 men on, 11 with 1 man on, 1 with 2 men on, 1 with 3 men on...average of 0.44 runners on base.
Freeman has hit 38 HRS: 22 with 0 men on, 12 with 1 man on, 4 with 2 men on, 1 with 3 men on...average of 0.61 runners on base.
Donaldson has hit 34 HRS: 21 with 0 men on, 6 with 1 man on, 7 with 2 men on, 0 with 3 men on...average of 0.59 runners on base.
Are we starting to see the problem batting Acuna lead off?
Moving him from #2 to #1 gains him ~17 PAs over the course of a season, which is roughly 1 extra HR out of him. Problem is, the cost of that 1 extra HR is ~0.15 runners on base for each HR he hits. Multiply that 0.15 by the 40+ HRs he is going to hit each year, and that's 6+ runs left on the table simply due to the fact he is hitting so many solo HRs. That's half a win the Braves could gain with nothing more than the swipe of a sharpie.
Fact of the matter is someone else needs to be hitting in front of the Acuna/Freeman/Donaldson trio. There are several high-OBP low(er)-ISO options to choose from on this roster.