It was 2 Dagger + 3 Bolas vs 1 Dagger + 2 Bolas.
That is 730m vs 460m.
The reason why you were losing especially hard is the unit positioning.
The first attacks of your bolas went to the Dagger from ATOSTIC while he did attack your Bolas instead and significantly reduced their dps.
He even manually targeted the one Bolas which was not slowed down by the initial attacks and did get all of your units slowed while you killed 1 Dagger.
In addition to that he was able to position his remaining Dagger to hit 2 targets at the same time.

All I can say is that was perfectly microed by ATOSTIC .