Grasping at straws
I really do believe this though.
In the Zheng match. Zheng didn't break once. I never felt in that final set that she was going to win.
While in the Slava vs Serena match. Slava proved that she could break the Serena serve, and i felt that she could actually win the final set. Of course it didn't happen, but i felt it could happen more in that match than the Zheng match.
If you just look at the scorelines, it looks like Zheng was closer. But there is more too it than that