Baseball players are incredibly accessible before their games. If you go early enough, you can wait by the side of the field and they'll throw you a batting practice ball or some come over to sign autographs.
Getting signatures of athletes is a time-honored tradition and a massive industry. There's no denying its importance to preserving the history of sport — seeing anything signed by Babe Ruth is super cool — but I'd rather take a picture of my kids with an athlete when they come over to fans to sign.
It captures the moment for us and is really fond to look at. When I was a kid, we didn't have access to cameras the way we do now with our phones, which makes this possible.
Plus it feels more respectful to an athlete and less tacky — provided it's not a selfie. Selfies are more acceptable now, but those pictures always come out looking a bit off, in my opinion.
So if you're with your kid in a spot where an athlete thinks they're supposed to sign an autograph, just ask for a photo and have your child turn around. It'll mean more to everyone involved.