Oh, certainly! Learning to use my camera has been paying dividends that I can't really explain. I expect I'll keep getting better.
Biggest thing for me to learn now is how to work with a zoom lens. Then, get a better one. (Well, I say zoom, I really just mean telephoto. Right now I have a zoom one, but expect to move to a prime one eventually.)
And I think you are dead on, learning how they did things in the "good old days" is a huge skill that has been helping a lot. Things are a little tougher when my child is effectively running around at random right now. I expect that to change, as well.
The "big trick" to sports photography has always been learning the sport, and that's only a little less crucial now with, say, a 1DX or a D4/D4S than it was back in my manual-focus days. However, that's not going to be of much help when the kids you're photographing don't know the sport. Expect a comparatively large number of failed shots, and learn to laugh. A 400/2.8 L isn't going to help a whole lot until there's some statistically-valid chance of anticipating the action. (And it's godawful heavy and awkward as well as really good used car expensive.) As your photography develops and your athlete develops, you'll know when (or if) it's time to go for the big guns. In the meantime, a fast 70-200 (with a good teleconverter for some shot types) will fill the bill, and unless you're printing huge, don't be afraid to crank the ISO a bit to keep the shutter speed down. (Look at the pictures, not the pixels. There ought to be some sort of license required to zoom in to 100%.)
I've definitely learned this one the hard way. At first I was excited about having everything at super low ISO. Now, I take a few quick shots to see what the lowest I can get away with and still get quick pictures.
Heck, often times I'm happy to just take videos. Really liking how well they turn out with this camera.
Actually, if you're on a soccer field, and the kids are far enough away, there's a good chance they're focused at infinity anyways, so you may not even need to focus (although your camera should be set to MF) as long as you've got the aperture small enough to give you wiggle room on the DOF.
Biggest thing for me to learn now is how to work with a zoom lens. Then, get a better one. (Well, I say zoom, I really just mean telephoto. Right now I have a zoom one, but expect to move to a prime one eventually.)
And I think you are dead on, learning how they did things in the "good old days" is a huge skill that has been helping a lot. Things are a little tougher when my child is effectively running around at random right now. I expect that to change, as well.