According to the AP:
"In a podcast uploaded to YouTube in June, Leeward said major changes were made to the plane before this year's race. He said his crew cut five feet off each wing and shortened the ailerons - the back edge of the main wings used to control balance - to 32 inches, down from about 60 inches.
"The goal was to make the plane more aerodynamic so it goes faster without a bigger engine.
"I know the speed. I know it'll do the speed. The systems aren't proven yet. We think they're going to be OK," he said.
Whether those changes may have had any bearing upon what happened is a question I'll leave to those more knowledgeable.
Note: that podcast quote reportedly is from June, so there were several months in which to do additional testing. I don't want to imply that he hadn't thoroughly tested the modifications.