Re-watched every Harden possession, and even with the breakdown on contesting the stepbacks, White was great on defense. Not only was Harden missing much more than he made, White being able to stay in front of Harden reduced his assist opportunities in a big way.
Without White on him, Harden just went to the rim at will setting up scores at the baked for the bigs and setting up open threes. Once he blew by Mills and DeRozan et al then the help had to rotate hard and it was open season.
Sadly White just doesn't have the size/length combination of Kawhi/Green/Simmons to both keep in front and contest stepbacks.