Pierce was the third line of defense on that play (fourth, if you count Joe Johnson's reach-in). Williams played great deny defense on the inbound, and then, with Garnett, continued to play great defense, forcing Lowry into a very unconventional, wrong-footed shot. Pierce deserves credit for being in the right position and making a nice play, but it wasn't even in the top 10 of plays in the first round of these playoffs, albeit, hugely impactful.