Lol! Having read some of the comments here, I see nothing much changes on this board!

I’m assuming that the thread title is meant to invite / provoke a reaction & start up a debate, rather than to be taken at face value.
Prior to Wimbledon 2012 & his subsequent absence, Nadal did very well this year. He was the finalist at the AO & the 7th time winner at the FO. He played 3 slams & was in the finals of 2 of them, one on a hard court, at the AO. Therefore, anyone denying that Nadal's absence due to injury is very much a factor to be considered when evaluating the performance of the other top 4 players, should think again. To say that he is less than excellent on hard courts & on that basis, to write him off as a possible contender for the USO 2012 title, had he played it, is somewhat blinkered in my view. Had he played it, I would expect him to have done very well there. He was, after all, the finalist there in 2011.
However, that said, anyone denying the overall supremacy of Djokovic in 2012, is wide of the mark. He has had an excellent tour this year, maintained an outstanding consistency & is rightly world number one. He is, quite simply, the man to beat. He was the champion at the AO, the finalist at the FO & the USO & a semi-finalist at Wimbledon. He has had an excellent ATP record this year, and is deservedly the number one ranked player. Without question, he tops the list for best player of 2012. Following his superb year in 2011, he is in fact the best player for the last 2 years.
Murray is next as the 2nd best player of 2012. He reached the semi's at the AO , the final at Wimbledon & won the USO. Add to that his Olympic Gold win after beating Djokovic & Federer to win the top medal. He ends the year as world number 3. A remarkable year for Murray.
Next, at number 3 for 2012, I put Federer. Reaching the semi's at the AO, FO & USO, he won his 7th Wimbledon title and with it, regained number one ranking. His record number of weeks as world number one is a remarkable achievement. He has also had a good ATP tour season. He won the Olympic silver medal, and finishes the year, deservedly, as world number 2. To have achieved all this at this stage in his career is particularly noteworthy.
So for me, Nadal finishes the year in the 4th best achiever position, correctly reflected in his ranking spot. Of course his injury plays a part in this - but fitness is part & parcel of achievement and it would be remiss to diminish the achievements of his peers because he had to sit out part of the year. As far as I'm concerned, asterisks don't exist, and each player deserves what he achieves.
The most important outcome this year was that, after several years of domination by one or another player, there are 4 different GS winners, and each of the top 4 players has achieved something remarkable in his career. This makes it one of the most exciting tennis years for a while, and I hope it will be even more exciting next year.