How did the Grabber take on the tougher kids in Black Phone?

Loved the film btw especially the 70s aesthetic and the kids did a great job acting.

But Robin was literally the toughest guy in school and took down adult size guys with ease. How would the Grabber be able to take him?

Near the end there is an older guy that in a flashback Vance Hopper who was a badass as well.

The Grabber did't seem like anything special in his physical abilities.