It appeared to me that he was talking about the success of the design, not just the tanks war record. The IS2 was a great design in response to the tiger, but was also a great tank in its own right much like the Panther. That the Soviets held the IS3 back is also indicative that they had no faith in the design being anything more than a liability on the battlefield. A good heavy tank could have changed the outcome in Korea, Israel’48, and Egypt’56 or at least prolonged the wars.