I've suggested the process is rigged. I don't actually believe that and such a statement is born of frustration and not actual facts.
That said, people putting forth the narrative that it COULDN'T happen are just as delusional as those that say it did. Just because an accounting firm oversees the lottery doesn't preclude the process from mistakes (2017 Oscars, anyone?) and/or corruption.
There could be mistakes and those would be corrected as quickly as the La La Land mistake at the Oscars was corrected.
As for corruption, you do realize that there are also team reps from all the teams in the lottery also present at the actual drawing. So, for Bettman to rig the lottery, he would need to have anyone else from the NHL who is present, the accountants, 15 teams reps, and the TV crew that films the ball drop for later release all in on it. And then, all of those people need to stay quiet about it. And I'm sure that several of the people who have been witness to the ball drop in the past have lost or quit their jobs and may have an axe to grind with one of the groups involved. But so far, we haven't had any of them come forward.
And also, remember, Bettman would have to ask each of those people to be involved. So, for it work, there could be no one asked who said no or at least agreed to not to blow the whistle.
Not to mention, the risk that Bettman would be taking in attempting to rig the lottery. If it ever got out that he tried to do so, not only would be finished, but I think it would do serious harm to the league overall.
So, I suppose it could happen, but really the odds of it succeeding are so low, you may as well say it is impossible.