Why did I pull a base card while it’s special card is out

I'm pretty sure they just add the TOTW cards into the rotation with the rest of them (haven't been corrected on this yet) so they're fairly rare.

If you look at the probablity section, it's technically possible not to pull a card from a pack claiming you're guaranteed something (it will say you have over a 99% chance but won't commit to saying 100)