No doubt LeBron has slipped a bit on defense, it’s pretty obvious. He also is showing signs of slowing down overall and needs rest more often, doesn’t run back on defense etc.
I recall an interview of him where he said that he NEVER lets anyone know when he is winded. He works hard at hiding it by not tugging at his shorts, remaining stoic during deadball and timeouts, avoiding heavy breathing, not slumping or looking downward too much.
With 8 straight finals appearances, the guy has played 100-something games per year for 8 years in a row. Nobody can maintain that.