This is a good discussion and others have made the points I always make to defend the system we came up with 10 years ago.
There are some building blocks in the FA draft but they are not taken by conytenders who are busy taking the best players for their run.
PB value does have some merit but not very much at face value. PB value per PA or IP is far more apt to winning games.
Look at the top LL teams and you will see that they generally have a fairly low PB value.

Mike Bravard (PB)