I would suggest disregarding the "PB" value number. They seem worthless.
I look at the classic numbers:

For hitters...OBP, SLG, sometimes VORP, etc.

For pitchers...K/IP ratio, Hits/9 IP ratio, IP, ERA, Vorp, etc.

I tend to build a team trying to get the best actual players, and generally PB will provide a simulation that is reasonable.

Aramis, with his OBP .373, SLG .578, with 600 Plate appearances and solid defense is a top tier thirdbaseman. The marginal gain with Beltre's season is not too high, and I'd be very happy to pencil Aramis in at 3B everyday, and forget about 3B.