[Coda]

It's easier to hit the inner circle when it's bigger, which makes it easier to get a Nice! throw, and Nice! throws do give you a bonus to your catch rate, but you don't HAVE to hit the inner circle -- the catch attempt will fire as long as you hit the outer circle, and the smaller the inner circle is when you hit it the higher your catch rates are. The BEST result is to hit the inner circle with the ball while it's small, getting both Nice!/Great!/Excellent! bonus and the higher base catch rate for the smaller circle.

Gyms have major balance problems, unfortunately. If you didn't get into the game pretty much immediately at launch, you can forget having a meaningful gym experience until you're level 15+.