He was dominant in clutch during the Denver series. Averaged 8 points on 50% FG, 66% 3pfg, 93% FT over lastt 5 mins per game that series.
His stats vs LAC/Memphis are probably decent too in the clutch. His stats this season/playoffs were poor in clutch.
But to say he hasn't proven it is inaccurate based on previous playoff performances. Whether he can get back to that is another question...but he's only 25 so probably not peaked yet.