Moe Norman's Golf Swing - an Anatomical Analysis
Many visitors to this blog have suggested an assessment of Moe Norman's (MN) golf swing. It's easy to assess the manner in which the joints are positioned at the top of the backswing, versus how they are at impact, to comment on injury potential. However, it is important to study ball-flight in order to study which compensatory moves a golfer is making, in order to arrive at the ball, from his/her top of backswing position. Not that it matters, because the Minimalist Golf Swing will improve ball-flight for any skill-level of golfer, regardless of how good or bad they are (that will be a subject for another day).
Look at MN's rear-view picture at the top of his backswing. The two main positions to study are the lateral flexion of the torso and the rotation of the shoulder.
The spine has left lateral flexion, so that the right side is higher. This, compounded with a tight right scapula, position the right shoulder in internal rotation. Besides the internally rotated right shoulder, he also does not have much width at his right elbow, and although it cannot be seen here, his right wrist is extended (bent backwards). 
A down-the line series of pictures shows the compensatory moves he makes from his top-of-backswing position to get to the ball. The very first move during the downswing is a pushing forwards (towards the ball) movement of the right shoulder. As the scapular muscles are strongly contracted to keep the scapula in its excessive retraction, the entire shoulder girdle moves forward as one unit, rather than allowing the arms to drop down at the start of the downswing.
By the time the arms finally drop down, The right shoulder has come pretty far forward, so that his right shoulder is not 'closed' to his left, and he is therefore not arriving at the ball with an externally rotated shoulder, which would help the club arrive at the ball from the 'inside'. What saves this swing from an over-the-top impact is the straightening of the right elbow combined with exaggerated shoulder flexion (right arm moving forward) towards the far-away ball!
Note: Moe Norman's excessive distance from ball should typically produce a rather glancing blow at the ball for most golfers, but his given particular combination of movements and his very internally rotated right shoulder, at least his right elbow is able to straighten out, somehow. This might be a better option than Jim Furyk's. Furyk also has a very internally rotated right shoulder, along with a backward bent (extended) right wrist, and both these joints are forced to straighten out at the last minute, and in a direction they are not designed to perform ideally from.
Moe Norman's other idiosyncratic move, besides his excessive distance from the ball, is often termed his 'single axis' motion, which apparently refers not to any axis but to his swing plane, which has been shown to be virtually the same going back and through.
A similar swing plane made at the cost of joints positioned in a manner they are not designed to work best from, requires many downswing compensations.
The entire concept of swing plane should be redundant in golf for two reasons: 1. What we in golf term a 'plane' is not anything heard of in geometry. A Google result for 'definition plane' is "a flat surface on which a straight line joining any two points on it would wholly lie". Now golf's idea of a swing plane is that different body and/or club parts are supposed to lie on the same plane at different times!
2. Any club positions are a combination of several joint positions, so to discuss club positions such as swing plane at all seems redundant. So, for instance, an 'across-the-line' shaft is created by excessive body or arm rotation. Similarly a closed or open club face at the top is determined by left wrist position at the top, and so on. The Minimalist Golf Swing, if required to define any 'plane' during the swing, considers the plane to be that of the left (lead) upper-arm, which has a similar path in the back and through directions.
Special Note: Peter, the owner of the very popular forum 'Single Axis Golf Forum' on network54.com, explained what 'single axis' means in Moe Norman's swing (some google hits show 'axis' being mixed up with 'plane' as regards MN's swing!). See below for his comments and some additional questions/comments from an anatomical/biomechanical perspective:
Re Moe Norman from Single Axis Golf Forum: 'Single axis' is not a reference to swing plane. When the grip is placed in the lifeline of the dominant hand, it creates a single axis, three lever system in the dominant arm. This allow for straight line hammer motions (an Ideal Mechanical Advantage stroke). - From US Patent 5,803,827 The only relevance of 'plane' is that the movement of the trail wrist into impact has no pronation or supination and therefore the 'three lever system' (forearm, hand & club) acts within a plane. Questions and comments from the minimalistgolfswingblog: What would be the common ‘axis’ of rotation of the trail forearm, hand and club? Which is the common ‘plane’ that those joints all remain on into impact, and for how long are they on that plane? Moe Norman’s ‘hammer’ is one way to straighten out the elbow, not the ideal way. The elbow is one of the middle joints of the upper ‘closed kinetic chain’, which comprises both shoulders, elbows, forearms and wrists, when they hold onto a golf club. Middle joints (ie. not closest or furthest from the spine, to phrase it in lay terms) inevitably get ‘stuck’ in awkward positions when joints on either side are incorrectly moved. So, when the trail (Moe’s right) shoulder is in internal rotation, the elbow is unable to straighten on the sagittal plane, as it is meant to, based on its design. [Anyone performing a bicep curl does so in front of the body, not to the side, because that is how the elbow works best]. Some people jump up on their toes, some straighten or ‘early extend’ their spines, and in Moe’s case he pushes his trail arm forward (technically a shoulder flexion) in order to somehow straighten his right elbow. The ideal way for the elbow to straighten is when the trail shoulder has been kept in external rotation throughout the back- and downswings - not easy to do with most swing styles. Thus, most swings require some downswing compensatory move!