You have done absolutely nothing wrong. At all. The lens is at its widest aperture, f/4. The ISO level is high on a small-format sensor, at 1600 ISO. Your shutter speed is 1/1000 second, which has frozen the batter; the only thing that is not 100 percent frozen is the ball leaving the bat. The ball is just ever-so-slightly out of round, but it's not elongated, like it would have been at say 1/500 second or 1/400 second.
I pulled the image into Photoshop. I adjusted the levels in the red,green,and blue channels individually. Your original exposure was adequate--not under-exposed at all. This is basically as good as your particular camera/zoom lens camera will do at ISO 1600 under open shade conditions. The photo will someday become a cherished family memory. It looks pretty decent to me,all things considered. If you want a better lens, you would have gotten significantly higher resolving power and higher contrast shooting with the Canon 85mm f/1.8 EF lens, but this is decent for a consumer zoom shot wide-open at f/4. As a smaller image, it looks quite good; pixel-peeping it and the quality's not as good as it'd be if you bought a new camera and a new lens, but hey--this image shows a nice scene, good timing,good focus,happy group of backyard ballplayers.
A home photographer could not have made this full-color image in 1975 on color print film with an ISO of 100 and a small,light zoom lens...