He is both "strong" and "fast", really really fast, btw.
__________________ Yani Tseng, Go! Go! Go! Yani Tseng Did It Again! YOU load and sustain the "LAG", during which the "LAW" releases it, ideally beyond impact.
"Sustain (Yang/陽) the lag (Yin/陰)" is "the unification of Ying and Yang" (陰陽合一).
The "LAW" creates the "effect", which is the "motion" or "feel", with the "cause", which is the "intent" or "command".
"Lag" is the secret of golf, passion is the secret of life.
Think as a golfer, execute like a robot.
Rotate, twist, spin, turn. Bend the shaft.
My guess is that he is pulling from the top--look how the club shallows-out on the downswing. Then he may switch to a driving (hitting) action once the club reaches the bottom of the pully thru low point, thus a 4 barrel swit. Just a guess. One thing is certain he is a very strong and quick Dude, and compression leakage is not a concern.
He may have components of both, but it appears to me he's driving that right side. Just don't see anything that indicates the class (snead, els) swing. Doesn't appear to be a lot of pulling with him.