If this is the case then directing people to have their shoulders 25-50 deg open to the target (horizontal plane) is totally incorrect.
Incorrect is an interesting term. It might be incorrect technically but that advice is a lot better then telling people to 'face the ball at impact.' IMHO of course.
Hmmm, this is especially true of folks who are using strong grip swings. Strong grip swings work best with the body open at impact. This is one very good reason why Dr. Mann's data might be out of date. I believe that there has been a significant trend towards strong lead hand grip swings on tour since Dr. Mann did the model. Dustin Johnson is one good example.