He is a bit smaller then tennis ball? So he is like 3"? The baby i consider up to 2-2,5" for cranwelli or ornate.

If he is eating ok in his 10 gal, then it is fine, but pacman frogs are getting stressed up easily in big cages, especially if it is very open. If that happens they stop eating and then it is all new set of problems. So just watch for that and make sure you cover 3 sides of the enclosure, put a plant(s).