I know it wasn't quite as late, but I remember just lady year Boston was up 20 in the 2nd half against the Knicks game 1 at home. Knicks won in OT. Very next game, Boston is again up 20 in the 2nd half. Again blows the lead and loses game 2 at home. 3rd game of series, Boston is up 25 at halftime. Boston wins that game by 22 and we all thought it was good. Boston up 11 at halftime of game 4. 3 minutes into 2nd half, lead up to 14. Outscored by 22 the rest of the way to lose by 8 and Tatum gets hurt. Boston wins game 5 by 25 before losing game 6 by 38.
The next series in game 1, the Knicks are up 111-94 with just over 6 minutes left and we're up 119-105 with just under 3 minutes Ieft. The Pacers won in OT. Game 3 it was the Pacers turn to blow a 15 point 2nd half lead.
I say this because it is just 1 game and the Knicks obviously have a propensity to have wild swings in their games. There is no reason thst Cleveland can't go up 20 again in game 2. If they do, hopefully their coach calls a timeout and doesnt let them collapse with poor coaching decisions.