I don't see anything in the instruction manual about the difference between VBD Start and VBD bench; all it has is a terse explanation of VBD.
Take a look at this article.
http://subscribers.footballguys.com/apps/article.php?article=13bryant_vbd
That's Joe Bryant's original article on VBD. It explains what the concept is, what the logic is, and why it's important. It's a fine article that made an impact in the game, and is an example of the kind of thing that made Footballguys the place to go for people who are quantitatively focused. There are plenty of other similar articles from Drinen, Stuart, and the rest of the crew over the years that have this kind of detailed analysis.
I don't see anywhere that the calculations being done by the new DD are being described in a way that a user can evaluate their agreement or disagreement with the methods. I've always thought Joe's Secret Formula was wrong, for example, and thus I never used it, but that was my choice based on hearing the logic behind the numbers. "obv not all bench players go for $1, hence Goff" is not an explanation that's useful to me. If I had just $4 to allocate, and I had to choose between $3 for a QB23 and $1 for a baseline WR, or $3 for Devante Parker and $1 for a backup QB, which should I do?
I think it's pretty unlikely that QB23 is worth more than $1 in a $100 12-team start-1 league. Frankly, with the difference between QB9 and QB17 being only 22 points, it's hard to see even QB12 being worth much more than $1. Would you really pay $9 for Derek Carr with Matt Ryan, Joe Flacco, Tony Romo and Andy Dalton on the board? That's what the new DD says you should do. Carr is projected to score 12 points more than Flacco. Would someone who took one of the top 12 QBs really pay $8 for Flacco? (Answers: No, and no. Flacco went for $3 in our league last year.)
In the new DD, there's no way I can fix what I view as a fundamental problem in the calculations. It's allocating probably $50-$75 too much of the pool money to QBs. If I crank the QB positional adjustment all the way down, the backup QB values fall in line, but the top QB values drop too much. And the Studs and Duds behavior seems completely random. With Studs and Duds in the middle, Cam Newton is worth $14.75. With Studs and Duds at the right, he's worth $14. With Studs and Duds at the left, he's worth $13. That makes no sense.