On October 18, 2016 the Eastern Conference odds were
-215
+500
The Cavs as the defending NBA champions and the upstart Celtics were still very far apart. Which makes sense, since Boston hadn't yet played with Horford and lacked a transcendent player (or even a HOFer - remember this is before Thomas took another jump).
Just before the playoffs, on April 13, 2017 the Eastern Conference odds were
-275
+425
This was of course before Boston advanced to the ECF and had only been a 1st round and out team, but had been healthy. Boston's odds got better, but the Cavs were even more favored entering the playoffs then at the start of the season (James being healthy will do that). This despite Thomas putting up a top 5 MVP level performance on the season.
After Boston beat Washington and before game 1 of the ECF, the odds were
-600
+450
So, the Cavs got on a roll and Boston struggled with Chicago and Washington, so the Cavs became much heavier favorites, which was borne out in the series.
At the start of free agency
-150
+325
The Celtics had closed the gap a bit after getting experience and the anticipation of Boston acquiring a prime free agent or making a trade (or both) and the Cavs basically looking like they would be bringing back the same core with only some minor changes to their bench.
Then when Boston finally makes it moves, the gap only slightly narrows a bit more.
-140
+275
So Boston has closed the gap, which I've acknowledged all along, but the gap is still pretty substantial and they show the Celtics are still a player away (which is what ownership has said all along). I'm sorry that you disagree with Wyc and Ainge, but they know the team is a player away. They also know that James is getting old and there is no point in giving away the kitchen sink to only slightly improve Boston's title chances (that means the Warriors not just the Cavs come into play). Ownership is trying to have its cake and eat to, I personally think that is the wrong decision, but I understand why they are doing what they are doing.