Whether that may be true or not, you can't use DRTG/ORTG and NRTG in that manner. Sample size is far too small and both teams don't play the same competition. The main reason the Cavs have the third best DRTG, isn't because they've had the third best defense (or are the third best defensive team) in the playoffs. It's because almost all the other teams' DRTGs have been affected by playing against either the Cavs or the Warriors offenses, respectively. It's the reason why teams like the Jazz are ranked 10th out of 16 in the playoffs in DRTG, but were ranked 3rd out of 30 in the regular season. It's not because their defense lost their abilities or structure, it was because it was affected by playing the Warriors offense in 4 of their 11 Playoff games.
shyt the Raptors had the second best DRTG after the first round (100.7 against the Bucks, and were one of the best defensive teams in the RS), but then had a 118 DRTG in the Cavs series.