Have you ever edited the video from your 5D3 before? Do you know how to make sure that you are rendering at the proper fps to avoid ghosting and the like?
If I was going to do a short clip of highlights, I'd use my 5D3, but I'd plan on shooting the whole match and ending up with about 2 mins of usable game footage + off the court stuff, which is much easier. It'll probably require at least 16GB worth of CF (Make sure you have the right speed of card 60Mbps minimum).
Here are some general tips, assuming that you can get yourself into video mode
1. Find the right white balance. Gym lights can be pretty ugly, and I'd want to try and set the color temperature(its the mode that says K when setting white) to something that looked good on the camera's LCD.
2. I'd probably start with my 135 lense, and aim for f4.5-5.6. You really want the ISO to be below 1600 for the best look, but i'd go as high as 5200 if I planned on down scaling to 720p. If you find that you can get a lower ISO than 1600, I'd close down to f8 first, then drop ISO as far as it will go.
3. Shoot in the standard picture profile (default). Go with 30fps, and the slowest possible shutter (1/30 I think). This will make it as smooth as possible. Also. I'd stick to 1080p, so I can pan and scan, and re-frame shots in post(see #4), since panning live is going to be hard.
4. For Action: Take short clips(<10 secs), since auto focus in video mode is totally nerfed, tracking and zooming is going to be effectively imposable (until you become a Jedi master). You need to frame a bunch of shots, and get lucky. Turn off IS (image stabilization). Use your tripod and make sure you know your focus point by using the zoom button while in live-view.
5. At some point, switch up your lenses, and get some wider shots with the 35mm. If you want to get fancy, you can try and use your zoom to get extreme close-ups of players faces. Remember, if you plan on making the cut in 720p, you can crop to enhance zooms.
Give this a try for the first game. If everything looks like sh*t, then go to the camcorder. I think you'll know one way or the other.
Let us know how it works out, and post a clips!
Also, if you plan on doing this stuff in the future, and you have more time to practice, i'd learn how to use one of these:http://www.bhphotovideo.com/c/product/579907-REG/Glidecam_HD_2000_HD2000_Stabilizer_System.html