Race results are fairly telling at this stage of the season.
It's interesting to me that Nole has around 1500 more points while having played 3 fewer tournaments. Usually Federer gets kudos because of his scheduling, but he's evidently felt pressed this year to keep up with Nole. Or maybe he felt that since Nole had so many points to defend, he should play everything he could in order to claim the number one spot.
Nole has 560 points to defend for the rest of the season while Fed has 3000 points
so getting some points and prevent Nole from gaining more in Shanghai definitely helps. Especially Nole does not sign up for Basel where he will lose 180 points. Nobody knows what will happen for the last few weeks and whether Nole will gain more points on Fed.