I can guess where you are going with this, but I would say that his most recent experiences would have been with Philip Rivers and Justin Herbert. So, he is most likely talking about how he worked with them to be good on 3rd down.
Looking at the potential Bears QB situation, whether it's Fields or Williams, I think that is really one of the bigger question marks for both - can they stay within the timing of the offense. We already know that Fields has struggled with that in the NFL and is one of the biggest areas he needs to improve. There is evidence that Williams can do it, but the offense that Riley runs means it was never a consistent thing. So, that also ends up as one of the bigger questions on how Williams will acclimate to an NFL offense.
You have to think though that there are now enough weapons that someone (Moore, Allen, Kmet, Everett, Swift) should find a way to be open on a given play now. So, it will be a matter of can the QB make the right reads, pre-snap and post-snap, to find them and deliver the ball within the timing of the play.