If it wasn't for Lebron, Irving would be playing hero ball all day without a care in the world. Before Lebron came into the picture, he couldn't lift the cavs to an 8th seed in the terrible east. Similarly to Draymond Green running the offense through him in golden state, Lebron does the same for the cavs. Steph curry still finds a way to average 6.6 assists, Irving is averaging 4.4. When Lebron takes a rest on the bench, he should easily be racking the assists up, but instead he plays 1v1, and he's not a good passer so there is also that.
Last year the teams in the east, and arguably the west were playing much worse than they are now.
Heat = No bosh and have a different team
Pacers = No PG13 and have a different team
Detroit = Different team
Charlotte = Different team (no jeremy lin or knick batum etc)
Jazz = Different team
Celtics = Got much better
Raptors = Got better
Wizards = Arguably better, just started off bad this season
Magic = Got better
Spurs = Got better, different team
Thunder = No KD
Clippers = Playing better
Grizz = Playing better
Mavs = Different team
Lebron has 2 more years or so of dominance before I see him deteriorating to the level which you speak of. I still can't see any team in the east beating the cavs in a 7 game series, even if they don't have home court advantage. Regular season is just that. He plays his best in the playoffs, and statistics show he's as clutch if not more than Jordan when that time comes.