Djokovic leads by 1100 points, but having a lot of his points in 500s means he can only gain 820 points by winning MC and cannot gain anything in Barcelona, while Murray can gain 1500 points in Barcelona and MC by winning both. This is why the potential difference between them is not the same as the actual points won so far difference.
I get that but, when counting down from RG to now, we don't count MC. So he can "gain" 1000 points from MC. Also agreed that Murray can gain 1500 but the difference still remains 500 points which is still smaller than the difference of 1100 points.
Anyways, I still think Murray and Djokovic will be non-factors in the race to 287. Even if Djokovic regains form, he will be exchanging points with Nadal thereby ensuring Federer's spot.
I think the best bet now would be for Djokovic and Nadal to keep winning alternate tournaments so that no one player gets the chunk of points.