Each PCL team gets two challenges per game that count toward both ABS and check swings. Expect very few swing challenges, as they are much harder for the human eye to judge and much less valuable than ABS challenges. It'll be interesting to see how teams learn to leverage this.
For those wondering how the new check swing rule looks. All of Triple-A has gone to this new definition of a check swing. Players still appeal to base umps first for a ruling on a check swing. In the PCL (not IL), if someone disagrees w/ the ruling, they can then challenge it.