Pochettino was main person behind success of this Chelsea because he has done good job and keep things on good level which helps Maresca for having good end of his first season at coach of Chelsea which is having strong case of ending their season in top five clubs even nine matches remaining and things can take changes, but their case is good for keeping this momentum.
I don't believe Pochettino is the sole reason for Chelsea's success. Team success is a collective effort, not just the work of an individual. That said, while Chelsea are in contention for a top four finish, they must avoid any form of complacency and be more clinical in front of goal and ensure they keep a well defensive stability to secure the desired result. Otherwise they risk missing out on the top four spot.
I don't understand how Pochettino is considered the main reason for Chelsea's success. I won't deny that Pochettino was able to stabilize chelsea to some extent. But Chelsea's success came because of Enzo Maresca. and of course Chelsea's players have also worked hard. Enzo maresca's match strategy is good. Maresca has also been able to strengthen the bonding between the players . Because of this, the players are very confident now . Chelsea's team cannot be called very strong yet. Chelsea's performance is still erratic. However, with the help of Enzo , Chelsea's performance is now quite stable.