In his column for the Daily Star Sunday, Souness wrote: "For me, Chelsea and Ancelotti were the perfect match. He had been at big clubs all his life and was a big player himself.
"For five years, they had been crucial players in Chelsea's success.
"That was the difference at Chelsea last season. They didn't win anything and that cost Ancelotti his job.
"They still finished runners-up in the Premier League after doing the Double the previous season but that wasn't enough to keep Carlo in his job. It showed the pressure managers are under at Stamford Bridge.
"And the pressure will certainly be on Ancelotti's successor Andre Villas-Boas this season.
"I've already made my feelings clear on that appointment - it's an enormous gamble. Villas-Boas is a young manager at 33 and he has only had one good season at Porto."