That noise is definitely Frank Shamrock's strike to the body.

Before any asks about the sissy punches: these fights took place under the weird-as-shit Pancrase banner, which was based off of professional wrestling rules (though the fights were not "works") and did not allow closed-fist strikes to the face.

Also, Bas rules.

He would do well I think as he was a fairly versatile fighter once he worked on his ground game.