I see. When I'm saying GB/FB, I'm talking about rating. I won't give away my formulas, I've done a ton of work on them, but assuming non-weighted numbers, this is what I mean.
Con 80/80
VR 80/70
VL 80/70
VEL 80/80
P1 80/80
P2 75/75
P3 70/70
P4 65/65
As a general rule, the 1st number pitcher will be more effective simply based on splits. But, if 2nd number pitcher has a GB/FB like this, GB/FB 50/70, they're like to produce similar WHIP/ERA. P1 will give up more homers, P2 will get more DP.
Again, I used round, non-weighted numbers. No way GB/FB is nearly as important as control/VR/etc/etc. VL/VR are not the same value. But, if both pitchers come out at 660, similar WHIP/ERA will be the result.