Registas in general were great 20 years ago when the other team had forwards who couldn't be bothered to run. Nowadays it's completely different.
But anyways, I usually defend Pjanic because even if he would get marked, he would at least be capable defensively. Not amazing, but capable. That is just not true anymore.
The opponent can punt the ball anywhere near our Bonucci/Pjanic area and will 100% retain it.