Doc Rivers already starting to blame everyone but himself. Yeah I'm sure the cooks and drivers and everyone else would have really helped on the court

I don't think it is a lack of professionalism. It is a lack of talent & athleticism. They just do not have enough foot-speed on defense.
They have one of the worst defensive PGs in the league.
They have one of the worst defensive SGs in the league.
They have one of the worst defensive SFs in the league.
And they have one of the slowest least mobile centers in the league. You can work with a slow immobile center when you have big active athletic talented defensive perimeter guys (to shrink the floor). When you have bad perimeter guys, that all falls apart.
It worked with Jrue Holiday and a pre-injury Khris Middleton. It doesn't work anymore. It wouldn't have worked even had they kept Jrue. Middleton just isn't the same defensive player anymore.