With as many rookies and 2nd year players getting minutes at the same time, there is no coach anywhere that was going to get reasonable team defense out of that squad.
Telfair? Gerald Green? Al Jefferson? Gomes transitioning to SF? Injuries to Perk, PP, TA, etc.?
I'm not a big Doc fan, mostly during the regular season, but let's be fair.
Blount, Pierce, Payton, Lafrenz, Walker, and Davis were anything but rookies. Blount and Pierce were excellent defenders under Obie and Walker was sort of adequate. Lafrentz was a good defender throughout his career. The blitz defense Rivers implemented is a gimmick defense that is commonly used a few times a game. Like Pitino's balls-to-the-walls system, it isn't a full time pro defense.
The NBA all defensive first team couldn't defend in Rivers' "system" pre-Thibodeau. Because there was no system. The only players who improved defensively at all during Rivers' tenure pre-Thibodeau were the bigs under Cliff Ray. But there was no system so the only thing that improved was their footwork. They were still always out of position. You could make a case that most players regressed defensively.
The fourth season could be written off because they were tanking....Players were "injured"
.
Going to be interesting if Rivers is on his own again.
Without trying to defend Doc, which I am rarely inclined to do:
LaFrenz had no lateral movement, and his career was basically over.
Ricky Davis? Defense? On-ball, sometimes, but he was a ball-watcher looking for a cheap steal, not a team defender.
Blount got good at rotating for a block under Obie, but that's it.
GP was on his last legs, and didn't have what he once did (I watched him in the '90's in seattle while stationed at Ft. Lewis).
Antoine Walker would routinely get beat off the dribble, then make a swipe.
Q: how well have all these veterans played after leaving Boston?
I think the record on that is clear. The team was what it was because of talent, not coaching.