Hi Frankin, welcome to the forums
I follow my local basketball team and am usually there with my camera so I've gained a bit of experience doing it and it is a bit of a technical challenge. I started off shooting with a 10D and a 50mm F1.8 so I am familiar with that setup and the challenges using it. I can see some shots where you have good timing and a lot of my initial shots looked like yours too. I think I have progressed a wee bit so am able to give some advice I think, though there are many on here that are far better than me.
First of all a lot of people on here wont follow links, so grab the bb code off flickr of 3 (or 5 at the most) of your best shots and post them here, that way you will be more likley to get feedback.
I notice some issues with your shots, what settings were you using? I normally use ss 1/800th sec (you may be able to get away with a slightly slower shutter speed but I'd suggest not below 1/250th sec), f4 or 5.6 (otherwise I run into DOF issues when so close to the action with a 50mm but if I'm further away I use a 70-300mm). Single or expanded AF-point and AI Servo, CWA metering mode with the camera in manual and auto ISO, high speed burst mode and I shoot jpegs to get the maximum framerate with all in camera processing off. I compose the image centrally and try to shoot wide and crop later in post. I also set a custom white balance.
What I'd say about composing these kind of photographs is conflict is interesting, I've noticed a marked improvement in my shots since I started trying to show the conflict between players on the court. I'd also say that you need to show the face of at least one player and ideally the ball needs to be in the shot too. Try and crop out anything unnessicary and include the whole of your player (yes, I still crop off a lot of feet too

) try and focus on the main player who is almost allways the guy with the ball.
I think there could be a nice wee series in here of the interaction between the small player and the big guy in the centre, but the basics of exposure, shutter speed and framing need to be right too.
Bear in mind as well that I might go to a game and fire off 700 odd frames and get 3 keepers if I am lucky. One of the guys around here that shoots some top class sports action is imagemaker46, I'd have a look at some of his shots.
in fact here is one of his threads with some cracking action shots, never mind the bs that goes with it.
http://www.thephotoforum.com/forum/photojournalism-sports-gallery/336344-beach-volleyball.html