Woodley has trouble exploding when he does not get an opening, like against Wonderboy or Maia, who are composed, technical fighters. GSP was extremely conservative and technical, on top of being a superlative athlete, and would only throw quick jabs, straights, superman punches, leaving minimal openings for countering with his stand up. Bad night for Woodley.
He is also a lot better with his jitz and a very good wrestler, so if it goes down things would be murky for Woodley, quick.
That said, GSP wins via a comfortable, possibly boring stand up jab-fest.