Heh, yes it does. Thanks for the tip. I was already using it, though.
The problem is that these days, tank builds spread themselves out to cherry pick AC and PRR and such from wherever they can get it. This impacts BAB, which in turn hurts PRR. A lot of builders will post their PRR in a screen shot. If you see something like 18/30 in the BAB box that means it's buffed with Tenser's or Divine Power and thus probably not actually played that way -- at least I've never seen an R10 tank stop and scroll every 66s and my tank sure doesn't do it either.
PRR increases by 2xBAB for heavy, 1.5x for medium, 1.0x for light, and 0.0x for cloth. If you have BAB=Level, you then have the most PRR you can get out of your armor. It also directly adds to accuracy and determines which attack rate table you use (with BAB=25 being the top attack rate table). So, it matters for tanks and melee mostly.
Why just melee and not ranged, too? Because ranged can reach the 86/m ROF cap with low BAB. It still matters for accuracy and PRR for ranged, but it doesn't hit all 3 factors the way it does for melee (and I'm more OK with less PRR on my ranged).
This is irritating when building a tank or melee these days. As the level cap increases more and more, I suspect it will become more than irritating and end up side-lining low BAB builds. There are all kinds of ways to deal with the issue -- I can think of 3 more ways that I didn't post, but I already tend toward TL;DR. Should prolly trim what/where I can.
BTW, if you already know all this, not trying to patronize -- there's bound to be 5 or 6 newbies out there somewhere wondering. Maybe they'll read this someday.