When you're old, you can maintain a relatively high level of fitness..... but once you lose it, it's gone. You can't get it back like you can when you're young.
It's like imagine an 80 year old that's really mobile and active and in really good shape. One day they trip and break their pelvis or their leg.. and then, bam, they're disabled for life and headed to the nursing home. Whereas a 25 year old breaks the same bone and is back into prime shape a year later.
The same applies for physical fitness and sports competitiveness.
Tito has stayed active and competitive. He never really "retired". He's maintained a decent level of competitiveness.
Chuck retired. He declined and his training videos prove that he didn't get it back.