My opinion -Ruiz did not take it seriously. I saw him munching on pizza on consecutive days weeks before the fight -AJ took it seriously. And fought more carefully -AJ probably could have won the first fight if he executed the game plan he did today
AJ was light on his feet moving side to side to confuse the slow footed Ruiz, Andy didn`t seem to know how he beat AJ in teir first clash, he should have studied a tape of that fight, his team are useless and he underestimated AJ`s jab and movement, he didn`t believe AJ was out-boxing him before being caught in the 3rd of their first clash and had no plan B. Ruiz should have hired Usyk`s team to train him on moving in and out, his feet looked like they were in cement and he was far too large, he has to fire his team.
Of the four options listed above two is the closest. But it wasn't a lucky punch. Ruiz fought his ass off and capitalised on his opportunity. This time round Joshua adjusted his tactics and executed his gameplan to perfection. Ruiz took his eye off the ball, but likely wouldn't have done much better at any weight.