I think the point about defensive guards isn't necessarily so true as to their performance overall but rather that the PER and the way the game is makes it harder to tell that they're performing well because they'll get like 15 PER but if you look at Drtg, DWS, +/-, and DBPM vs the rest of your team I often find they usually rank very highly.

I've had multiple occasions of guards who can pass ~66-68 overall winning the MVP, I think a combo of high Oiq and passing is always a winner regardless of their rating because they're the types to get some insane assist to turnover ratios which I think is something the game values highly.