I think there's truth to this.
In the Chicago game the Kings' turnovers, which began with five in the first quarter, gave the Bulls a big boost of confidence early in the game. You could almost see the Bulls thinking, "We're in this thing. They are giving us free shots." For a relatively poor team, there's nothing like the opponent giving you free shots to make you feel more relaxed and confident in shooting the ball, thereby being on the "down hill slope."
In the Portland game, McCollum got it rolling in the first quarter and he was like a Olympic slalom skier on "a down hill slope" after that. It makes sense to me that some adjustments had to be made earlier to break the momentum, to add friction to slow the downhill acceleration. Whether Walton tried to make those adjustments or not is up for debate. We never really know how much of his instruction is implemented on the court. My own speculation is that Walton was giving Buddy the benefit of the doubt - more rope, if you will. Christie kept talking about the need for Buddy to run through screens, but we never did see that.
But now let me argue against myself.
In the Denver game, Harris was a man on fire in the first half. (Again, the man guarding him was Buddy Hield). Harris hasn't topped the 12-point mark in eight of his last nine games. The exception was the Kings' game, in which he finished the game with 25 points off of 16 attempts (over 1.5 pts/attempt, just like McCollum). The Kings did slow him down somewhat in the 2nd half and won the game, despite his fast start. But a herculean (and somewhat lucky) effort had to occur in order to do it.
P.S. IMO, it's no coincidence that Portland's game plan was to feed the ball early and often to McCollum. They knew full well who was guarding him. IMO, Buddy is going to be attacked like minnows are from barracuda in the upcoming games. Opponents see what works.