I think the techniques themselves are less important than the system behind it. One of the books in this trifecta of productivity books is Scott Adams' (the Dilbert guy) book. He makes the point that goals are for losers (as in, you're a loser for a long time until you actually hit that goal), and that you should instead focus on implementing some kind of system that you'll be able to succeed at and improve over time. So instead of saying "I want to lose X pounds", he suggests saying "I will eat healthy/healthier", which is much easier to accomplish and improve upon.
There's also a bunch of research that suggests that you will inevitably hit a plateau unless you develop ways to practice with deliberateness. Cal Newport calls it "stretch and destroy": stretch your current abilities to an uncomfortable level and embrace honest feedback, even if it destroys what you thought was good.
That's not necessarily fun though, so I would think about what you want to get out of softball. Could be that it just satiates your sporting and socializing needs. There's no need to strive for perfection in everything you do, but I firmly believe it's good to do everything with deliberateness.