The main question is, will VIT x a% + STR x b% = 100% of current AP or not? Which brings us to the following... (more napkin math to come)

Legend: cSTR = Current STR value, which is STR:AP = 1:1. nSTR and nVIT are the new after patch changed VIT and STR values.

Now what if:

nSTR = 0.5 cSTR.
nVIT = 0.7 cSTR.

We end up with a (nSTR+nVIT):cSTR = 1.2:1

Now left side and weapons would be stronger than what they give today. But left side (either VIT or STR) would be weaker. But with the above rate, we may have a better overall (or equivalent) AP rate by equipping VIT or at least get the same AP as a penta-melded set of accessories.

Regardless if it's a damage nerf or not, I do think that the new beefier tank shouldn't be dealing the same DPS as the current full strength built tanks who were "squishier".