Changing spec will definitely be an improvement, but that will not be a magic bullet to fix threat gen if he is not executing a good rotation. looking at the logs the issues appears to be rotation related rather than spec. I would concur that he would benefit from a "better" spec but I still believe the heart of the problem is in his rotation or execution of it. I could change to his spec and still generate sufficient threat, I would generate lower threat than I do now but as it stands I do not have issues with people getting close to catching up to me. I have experimented with various builds for that do not have ATtT, Impale, DW and did not have any threat issues but my overall contribution to raid DPS went down so I stuck with the DW build and UA Builds.
I like my women how I like my coffee, ground up and in the freezer.