What evidence can you provide to support this assertion. Actually, it seems more like an assumption than an assertion. There are many factors that contribute to a positive 2nd half scoring margin. Coaching adjustments is just one of many variables, but I see no evidence that it's the most significant source of the Blazers positive 2nd half margins.
For example, this team has been wildly inconsistent, more so than any team I can remember. They lead the league in both blowout wins and blowout losses. BTW, this wild inconsistency, to me, is a sign of poor coaching. This team has the talent to beat any team in the league on any given night and to regularly blow teams out by 20 points. But, they have also lost to some of the worst teams in the league and regularly get blown out by 20+ points. And I think this wild inconsistency, that has resulted in a very significant number of games that are not close, contributes more to the Blazers second half margins than any half time adjustments by Nate. When the Blazers are down by 20 in the second half, Nate rarely throws in the towel and clears his bench. He continues to play his starters in hope of a comeback, long after the opposing coach has put in his 10th, 11th and 12th men. So, our starters against their third stringers results in a positive second half margin. Ditto for when the Blazers are up 20 in the second half. Most other coaches use that as an opportunity to pull their starters and let them get some rest while getting the deep bench some PT. Again our starters against their deep bench = positive second half margin.
I also think the pride factor eventually kicks in. In spite of all the turmoil around the team, at the end of the day, these guys are still professionals and no one likes to get blown out on their home court. So, they play hard to try to cut the margin to something respectable. You could argue that Nate's half time speech motivated them to play harder and save face, but being a great motivational speaker is not the same thing as being a good coach that makes half time adjustments.
Of course, this is just my personal explanation for the Blazers having a positive second half margin, in spite of being 3-17 when trailing at the half. It's also based on watching Nate's teams running the same tired 4th quarter offense that was effective when we had a healthy Brandon Roy, even though Roy's long gone and the team has an abysmal record in close games. Based on the lack of variety, it seems to me Nate is poor at making game-to-game adjustments (we've also seen this in the playoffs for three years running). If he can't even make effective game-to-game adjustments, I see no evidence that he's capable of making effective mid-game adjustments.
The stats you provide show one thing, and one thing only: a positive second half scoring margin. They tell nothing about the cause(s) of that margin.
BNM