First time out with the 7d and new sigma

I am very raw yet and any help would be appreciated on what I could do better.
This is a new camera and lens and the first shots ever done and I tried sports lol. I also am a newb to PhotoShop so any pointers are awesome.

White balance looks off, a little OOF, and grainy.

The light is also very harsh in #2, its hard to shoot that new or not.

You have the perfect under $1500 camera for sports so I suggest reading up a bit on how to make the most of it

Any better today on the color etc?

The white balance in the last one is good - if you shot RAW you might reduce the highlights just a tad. As you choose F/2.8 for this one you reduced your DOF which blurs the attacker on the right. He should have been in focus. With F/5.6 or F/8 you might have done that. With a subject distance of 11m a focal length of 110mm and aperture F/2.8 your DOF is only 110cm (3.5 ft) while at F/8 you get over 3m (11ft). Not sure if you need 1/2000 - may 1/1000" would have done the trick as well or else up your ISO to 800 or even 1250. With a 7D that would not have made much difference in the IQ.