He simply needs to fill the zone. His pitches move so much, that it seems like he is still finding his release point. It is almost like Ashby -- when he finds the correct release point(s), he is unhittable.
I thought the Morocco over Netherlands was a mild upset until I looked at the FIFA rankings. Goes to show I don't know as much as I thought I did... LOL
https://inside.fifa.com/fifa-world-ranking/men
Here is another article from earlier this year about its use in the Florida State League...
https://www.mlb.com/news/check-swing-challenge-comes-to-single-a-florida-state-league