Batshuayi's switch was part of a transfer merry-go-round, with Aubameyang leaving Dortmund for Arsenal and the Gunners selling Olivier Giroud to Chelsea.
Out of the three, however, it is Batshuayi who looks the shrewdest piece of business so far, as he once again played a starring role for BVB on Thursday.
The forward smashed two second-half goals to help his new side to a 3-2 Europa League victory over Atalanta.
In doing so, he has now outstripped his predecessor at the club in terms of making a scoring start.
Batshuayi has reached five goals for Dortmund in his first three games, while Aubameyang needed no less than seven to reach the same mark.
If he continues in this vein the star might just prove the best signing of the transfer window - while Auba remains on just one goal for Arsenal from his first two starts.