This is not anything new.
During the initial days (Gavaskar era), most of the players were Mumbaikars. Unsurprisingly, given that Mumbai is the most successful Ranji team, far far away from any other team. After the introduction of IPL, almost every players of CSK played for the national team (the Golden era of CSK).
In CSK hardly 4 to 5 members only got selected to national team that too in different seasons mostly 2 or 3 in National team PXI in past .. unlike current national team RCB & MI players are playing as 'Almost Every Player' 7 to 8 players in national team like 'So Called Golden Era'