Is it up to five out of the several old players you believe Chelsea still has? There are currently only four older players left: Thiago Silva, James, Kepa, and Chilwell. When Pocchetino took over as Chelsea's coach, many were sold.
Inasmuch as Pocchetino has let go of so many old players, I don't think it's a risky move. He is simultaneously bringing in new players and letting go of old players, To balance the equation
There are more than 5 players on the squad already joined Chelsea since the last season. You can count it yourself here
https://www.transfermarkt.co.id/fc-chelsea/kader/verein/631. Old players doesn't mean they already spend many years, they are old players if they already joined since the last season. Please understand this first, dude!!
Sure, we all know that Pocchetino has sold many players. We can check them here
https://www.transfermarkt.com/fc-chelsea/transfers/verein/631. Note that on the list includes the loan players.
I don't say it is a risky move. But if they sold all the old players, it may bother the squad balance. New players need time for adaptation, it is not easily to perform with their best in a short time.