Ranking players sequentially is stupid. I much prefer tier ranking like the Athletic does. That being said there are 30 teams. If you did a round robin draft, 101 would put White in the upper middle of the 4th round. He probably should be a bit higher but he is not closer to the top 50 which would put him late 2nd round. This is especially true since he's going to be 5th best on the Celts.
Now they clearly aren't discounting defense when they have Smart at #59. No way I'm taking Smart late 2nd round. They have him ahead of Bane and Porzingis which is ridiculous.
This is important perspective. There are 150 starters in the NBA. Being top 100 means on average, you are one of the top 3 players on an average NBA team. I don't know where White should be exactly, but would he be a top 3 player on the 15th best NBA team? Maybe.
Another way to look at it is:
There are 5 positions in the NBA. So a top 100 divided by 5 means you are a top 20 player at your position.
I find that a more useful marker for who I expect to be "in or out" of top 100 lists.
I like that, it distills it down to a more manageable number of players, 20 vs. 100, but it assumes that the 20th best PG has the same value as the 20th best Wing or PF. White could be the 20th best PG but lower than 100 overall, for example.
As to White, the discussion on where he ranks as a PG is fair, I have not made a list but people seem to have him in the 20'ish range, which seems about right. The thing with White is that he can give valuable minutes to a team as a SG also, he is a classic combo guard. Other pure PGs may be better as a PG but can't offer that versatility.
I think that is the thing with Combo guards. They are not as good at either position as some others but the versatility to play both is valuable. It is true of other positions as well, such as swing/PF players. I tend to like to see the primary players on a team playing their natural position, but the Celtics and other teams have been successful with multi-positional players in the mix, especially combo guard (Smart, White, Brogdon).
I don't think a pure PG is all that important these days (and the Celtics did pretty well with Dennis Johnson as a starting combo guard back in the day), but if you start a combo guard at PG, there is some downside. Holiday probably leans more natural PG than White, Smart, or Brogdon. I think he is the guy to "have the ball in his hands", more so than White. White is not a natural PG, he is a classic combo guard. The result is he may not rank as high relative to all the natural PGs in the league, but how do you account for what he can give you as SG?