Blackstone
Brigadier
Well, that map makes it appear like two of the Vietnamese vessels came in first and attacked the four Chinese vessels.
Then the other two Vietnamese vessels came in from around the other side...attempting a potential pencer.
Problem is, that has to be coordinated and syncrhonized to be effective, or the other side can defeat each force in detail.
In addition, the second group of Vietnamese vessels apparently significantly damaged on of their own vessels with friendly fire, further reducing any advantage the Vienamese had.
Looks like the centralized PLAN task force defeated two South Vietnamese squadrons in detail, before they could coordinate their attacks against the somewhat weaker Chinese force. Kind of like what Grant did in the Vicksburg Campaign against Pamperton and Johnston.