I'm not even isolating it to that. Go back to the championship playoffs and you should recall that Ray almost cost the Celtics in every series, including the Detroit series. The only true great game he had in those playoffs was in the blowout win over the Lakers. It's easy to make jumpers when you're up by 30.
You're misremembering. Starting in Game 5 in Detroit, Ray scored at least 16 in each game (with games of 25, 26, and 29 points), and he shot 50% or above in 6 out of 8 games.
Last year against the Lakers, Ray lost his 3 point shot (with the exception of Game 2), but he played excellent defense on Kobe. Also, in Games 5 and 6, Ray played well enough for the team to win.
Ray was terrible in Games 3 and 7, but overall, he had a solid playoffs (finishing as the Celts' second leading scorer.)