There's some bad advice being given here.
If you use manual exposure [begin edit] in situations like this[end edit], make sure auto ISO is turned off. When you are shooting from slightly above the court, as you are, the floor (and advertising signs) will reflect light into your camera's light meter. When your lens is pointed towards the floor, your light meter will read at least two stops brighter than the subjects actually are. If there is some dark in the background to make up for the floor, the meter reading won't be quite as bad. When auto ISO is turned on, your camera changes the ISO to obtain what it thinks is proper exposure, so all your work with shutter speed and aperture is undone.
Exposure compensation doesn't help a lot either, because as you are tracking your subject, the background changes with every shot, but your exposure actually should change only slightly, depending on whether they are in mid-court or near the basket facing towards the darker perimeter of the stadium. But the exposure definitely shouldn't change based on the background, but on the subject.
My manual exposure settings for an average Division I gym using the 135mm f/2 are about like this:
Fixed ISO 2,000
Picture Style Contrast set to very low (next to the leftmost setting)
If possible, use a manual white balance reading taken from a gray card positioned vertically slightly within the 3 point line and facing the basket. You need to catch some reflection from the floor as well as direct illumination from the lights. Ideally, the card should represent the light reflected from a player's face and eyes as they are moving the ball towards the basket or shooting. If the lights are flickering, then you need to use a time value under 1/15th of a second to get a perfect white balance reading that avoids the red/brown or other color shifts. But when I am actually shooting the game, I do not force myself to use a slow shutter speed. Go ahead and shoot fast enough to stop action, which at the very minimum is 1/500th of a second. I virtually always keep it at 1/800th or higher. Even if 2/3rds of your photos have a terrible color cast, the the other 1/3rd of them will be fine, and it is better for 1/3rd of them to be sharp and properly colored than for none of them to be sharp because of motion blur.
For darker gyms, light quickly goes down by a factor of five. That's when I would go down to 1/500th and ISO 5,000 if there is also color casting happening, or just go up to ISO 10,000 if there's not.
A few gyms are actually one stop brighter than the case mentioned above, and so I would use that as an opportunity to bump aperture, ISO, and shutter speed each by a notch to f/2.5, 1600, and 1/1250th.
** One other thing, when I'm taking pictures of coaches, players standing there, and whatever isn't action, I have a separate body with either a 300mm or 70-200 lens on it, and in that case, I definitely will use a slower shutter speed, like 1/200th, if there is any chance of color casting, to make sure that my photos don't have that color problem. But for action, the weird colors on some shots are just something to live with, because slowing down the shutter speed would only blur their faces too much. **