The images you have posted look properly exposed and sharpness is fine to me. Maybe when shooting back lit, into the setting sun, I would bump the EV up a 1/3 to 2/3. You are stopping the action so your shutter is good. What are the current settings you are using and maybe we can tweak from there. Shooting soccer at that time can be challenging as you are loosing light fast and you will most likely be needing to make changes constantly, so just watch your histogram and make it doesn't fall off to far to the left.
A couple of things you will want to watch for.
1. The horizon is off in a few of your images, you should be able to fix that in post, but you will want to get a point where you don't have to be fixing that.
2. People want to see faces, so watch how may back/behind shots your do. I occasionally will take shots from behind to, but you will want to limit that number.
3. This one is probably the biggest one. Crop & shoot tighter. Most of your images are way too loose. Try and crop down to just the action.
You are doing just fine, keep shooting and I look forward to seeing more of your images.