90% of peak LeBron is still a great player but there are definitely some cracks. Dude has played an unreal amount of minutes in his career. He is 30 but he might be a lot older 30 than people think.
I think we can all agree seasons 5-11 pretty much capture most of LeBron's absolute prime. Look at his #s this year, you already see a decline.
Seasons 5 through 11 (526 games)
38.4 mpg, 28.0 ppg, 7.6 rpg, 7.1 apg, 52-35-76%, 8.7 FTA, 3.3 TO, 30.1 PER, .283 WS/48
Playoff Career (158 games)
42.5 mpg, 28.0 ppg, 8.4 rpg, 6.4 apg, 48-33-76%, 9.7 FTA, 3.4 TO, 27.7 PER, .242 WS/48
Season 12 (57 games)
36.2 mpg, 26.0 ppg, 5.7 rpg, 7.4 apg, 49-35-72%, 8.0 FTA, 4.2 TO, 26.2 PER, .196 WS/48.
Then there are the little things you see with your eyes, when he used to get the ball in transition it was over. He was the best transition player the league has ever seen, just a full throttle locomotive that either got fouled or scored. Now if there is an opening he takes it but a lot of times he either looks to pass or waits for the offense to get set. Defensively he doesn't make nearly as many weakside blocks as he used to. Doesn't run anyone down like he used to.
He's still a great player but not the all out force of nature that he was at his apex