I honestly don't think Sakura surpassed Tsunade because she has the exact moveset , minus Tsunade's raiton technique, so at best she's on par with her. You cannot surpass someone when you have the same moveset without showing anything new.
People say that her control is better than Tsunade when Tsunade was shown to release the yin seal without the use of handseals twice and if you look at it logically, Tsunade is maintaining another technique while maintaining Byakugou while Sakura just maintains the Byakugou only. Isn't that situation proof enough that Tsunade has better control? Same goes for her strength, she has to keep back a portion of her chakra when she's using her strength so that's why her destructive capabilities are not as big as Sakura's. If she didn't have to do that, you can imagine the amount of destruction she'd be able to cause.
Naruto and Sasuke have surpassed their previous tutors but due to Kishimoto not paying much attention to female characters, Sakura has not passed Tsunade.
This is my opinion