Here's a good article discussing four statistics that are propelling the win streak:
https://sports.yahoo.com/four-corners-success-celtics-besides-162920415.html. Summary:
(1) Cs are #5 in assist/TO ratio (1.88 for the season) but have upped that to 2.48 during the streak, which is #1 in the NBA. Note that Marcus very Smart has
25/1 Assist to TO ratio since he entered the starting lineup. No that is not a typo.
(2) Cs rebounding percentage (before last night's game) = 50.2, which ranked 17th in the league. In the first 4 games of the win streak, they were at 52.9, which would be 9th. Last night, they were at 59.3%.
(3) Cs are limiting fast break points by opposition to a league best (but that could be due to the opposition).
(4) KI's DRtg during the first four games was 99.7, which the article says was " better than any Celtic player averaging 30 or more minutes per game." Obviously, KI's DRtg is helped by Marcus very Smart guarding best offensive guard. KI had a DRtg last night of 89 (everyone on Cs had a DRtg under 92 last night).