Tiger Woods’ March 2014 microdiscectomy (back surgery), what it was, what could have cause it, what next?
The thick long, vertical strap muscles which keep our spines erect against the forward pull of gravity, and which have given homo sapiens the ability to evolve to an upright bipedal posture, are the erector spinae (ES) group, which have a direction of action which pulls the posterior spine downwards. 
Certain positions of the spine, such as when one bends forward, require the ES group of muscles to contract even more forcefully to keep one upright. As they do so, they put compressive loads on the spongy ‘discs’ which lie between the bony vertebrae of the spine. Maximum loads are imposed lower down in the spine - the lumbar spine - which must bear the weight of the entire upper body.
The discs are ‘shock absorbers’, and are made up of a softer inner portion - the ‘nucleus pulposus’ and a tougher outer area - the ‘annulus fibrosus’. Healthy disc pictured below: 
The long-term effect of bending or bending-plus-twisting - especially at great speed - such as during the golf downswing, is that sometimes the tough ‘annulus’ layer can get weakened and have tears/fissures in it, into which the inner gel-like ‘nucleus’ can ooze - ‘protrude’.
When material from the nucleus leaks into the annulus, there is said to be a disc ‘herniation’ (in lay, but incorrect terms, a 'slipped disc') which can range from the minimal version (‘protrusion’) to an ‘extrusion’ or even ‘sequestration’. (See pic. below) 
The typical direction of forces acting on a disc result in a backwardly directed herniation, that is, one which extends into the already small spinal canal which is 1 cm to 1.5 cm in diameter. As the spinal canal is so small and everything inside it a snug fit, even a small protrusion can pinch a nerve or a nerve root, causing pain not only in the area of the ‘pinch’ but also, sometimes, radiating down the entire leg.
One of the last options (after conservative physiotherapy and injections) is a microdiscectomy, in which a small part of the bulging disc is removed to ease the pressure on the nerve being ‘pinched’.
A very informative youtube video on the subject, by Dr. P. R Jeffords, states that outcome prognosis post-operation is very good. However, 15-20% people continue to have back pain and 5-10% can have re-herniation. 
So, has Tiger's coach Sean Foley had him make any swing changes, post-surgery, to prevent future injury to the currently well-healed back?
It is very obvious the backswing has been shortened, and been made even more compact (no side-to-side movement). The hands, as a result, seem rather ‘blocked’, coming across the ball much as a ping-pong bat would be moved when one intends to put right-side-spin on the ball!
An anatomical perspective of Tiger’s new motion(s) post his first event post-surgery below.
[Sir Nick Faldo got in a small dig by commenting that Tiger himself had said his swings might be rusty but that he’d got in a lot of short-game practice so why should that have failed too!]
The Full Swing: The set-up: This amount of forward flexion at address, excessive though it is, might not cause disc herniation, but certainly does not help relieve low-back pain. Moreover, it is so redundant. Forward flexion of the spine prevents the abdominal muscles from rotating and forward flexion of the knees prevents the gluteal muscles of the hips from rotating, and both are required during the downswing to aid both the production of swing speed and straight direction. 
The backswing: This new Nike shirt is perfect to see spinal movement. One can see clearly that the cervical, thoracic and lumbar parts of the spine are working at cross purposes, putting much greater stress and strain on the vertebrae, besides making it difficult to re-align them all for a good downswing. 
The new full-swing sequence: Other than a very slight ‘lag’ of the left wrist during early takeaway (which merely serves to keep the left arm making a low movement (adduction), which, in turn, reduces ‘combined-arm’ width at the top), the entire backswing is a pure left-trunk lateral flexion. The arm movement to the top is short, and combined with the totally ‘close-packed’ position of the right hip, all Tiger can do to start his downswing (as his arms cannot drop down with gravity nor his hips start with an unwinding rotation) is make a squat-like movement, lowering body level, then raising it up again in time for impact.
Although much has been written about a squat-jump type movement during the downswing being beneficial, it truly is NOT because all Tiger’s downswing serves to do it minimize the time span within which the club can connect the ball. When the right shoulder is ‘back’, it is able to present the club to the ball on an inside path, and thus increase the time-margin within which the club can reach the ball from the inside. With Tiger’s too-compact backswing, there is no time for his right shoulder to fall back (ie. become more 'closed'), and, in fact, his right shoulder and thigh drop down and forward steeply, ‘blocking’ his hands at impact, and requiring split-second hand-timing if he wishes to draw the ball. No golf swing should ever reply on last-minute small-muscle changes to alter ball-slight as that is too unreliable, too last-minute, and too many small joints must all move in correct sequence to pull it off.
The Chip Shot: For this small shot too, Tiger is making the same basic moves as for his full-swing. He makes a long club and arms arc, back-and-through, when all one needs for such a shot, (with the ball just a few yards from a green and not much slope) is a small, low-trajectory swing! His body at address has too much spine and hip flexion, and once again, the trunk flexes laterally for the backswing. Is there enough time for all those big muscles of the shoulders to undo the backswing-movements in the short distance the club travels during an approach shot? 
To add insult to injury, he makes a stand-and-turn type follow-through. As one stands one reduces the time-span within which one can connect the ball below its equator, and as one turns, one reduces the time-span within which one can connect the ball on its inside-right quadrant. With a stand-and-turn follow-through motion, only a part of the force intended for the ball actually goes into it (the cosine of the total amount!), the rest going into the ground or the air! 
His follow-through from what should be a putting-stroke-like chip shot is very complex too. His hips have rotated (why?), his shoulders laterally flexed (dropped down) on the right side, his left arm is in the beginnings of a chicken-wing (internal rotation) and his right arm excessively stiff, altogether resulting in blocked hands and an unreliable ball-motion.
To make the same full-swing style for a chip shot is bad enough, but to do so from a slope and expect good results is truly asking a lot, unless one practices tons of just such shots all the time, and even then, under conditions of arousal or fatigue, the brain will not as easily co-ordinate all the joint-movements required for such an unnecessarily complex movement.
The Putt: lots of pros suddenly seem to be using this style of putting - one always wonders who’s idea it originally was! How such subjective ideas get passed around in golf is truly amazing. Once again, the Nike stripes are in perfect position to aid an anatomical analysis! 
The intended concept is obvious - to make the swing a right-arm-only movement. How is it obvious? The shoulders are open at address, the right fore-arm is on the putter plane, and the right arm moves straight down the target line.
How it would work with different golfers would depend on how active their right shoulders are. In Tiger’s case, as his right shoulder and trunk drop, his left (LEAD, and should-be-radius-of-swing) arm gets pushed back, and will surely exert some influence on club direction, as, after all, the arms both hold the club. Also, his right shoulder’s range of motion becomes reduced because of the right side lateral flexion, and might be a factor in longer putts.
A prognosis? One website lists all of Tiger's injuries to date, and given his tight left arm and tight neck, one cannot rule out left shoulder and left wrist injury, he truly needs the Minimalist Golf Swing System URGENTLY and for all his shots from full-swing to short-game.
Try out all the described motions for yourself (without a ball, don't get his injuries!) and feel the restrictions of Tiger’s various swing positions. Write in any questions/comments.