I cannot remember the season in which so may top players played in all GS and TMS tournaments
If nothing changes till tomorrow, they are:
Stepanek and Safin just missed the list, as they didn't play only in Bercy. Is it some symptom of new times or something else ?
A combination of the byes in the TMS events, best of 3 finals, and the bribes to the top 4 to appear in both Madrid and Paris.
It's not been popular in some quarters of fandom but it's clearly worked.