The quirk supposedly gives you a bigger PCI during games at the time of day it applies to so your PCI during other games will be relatively smaller by default. There's no need to
penalize the games the quirk doesn't apply to for balance purposes. You just leave it at is and the player will remain relatively weaker during that time of day.
Now if someone truly is two different players depending on whether they're playing during the day or night (ie great at night/terrible during the day or vice versa), then you'd you need both a positive
and a negative quirk to reflect that. I don't think they've implemented negative quirks though. Someone else in the thread asked about that being a necessary addition for something like Lester's pickoff move for example.