Is there any chance we could have the PRs and KRs entered into the rotation on pulling starters?

I don't think they used to be, but I think they are now.

I've noticed multiple players getting reps at those positions in pre-season games. Although, it could just be due to fatigue or injury I guess.

My starters are definitely not getting subbed out

I just watched a pre-season game in CUST-9, and my starting PR was subbed out.

Strange.

Most likely fatigue, or possibly if your PR is also a starter he may have gotten benched via the "pull starters" setting.