BOF posted some great links that I also definitely recommend checking out. To answer the OP's question, it really all depends on the athlete. For athletes who are "tight" and generally have mobility issues, yoga is great. For athletes who have hypermobile joints and are "loose" yoga can actually be detrimental as it can increase the risk of injury.
To simplify it even more, most athletes either have a stability or mobility issue. Some are kind of right in the middle and can benefit from both, but most of the athletes I work with are either on one far side or the other. To determine what side you're on you can perform a simple joint laxity test. To view how to do the test go to this link here: https://www.youtube.com/watch?...CxjFL3Tk&index=4
To score this test:
Give yourself a 1 if you can make an angle of 90* or > between your pinky and top of your hand. Score this for both sides.
Give yourself a 1 if you can touch your thumb to your forearm. Score this for both sides.
Give yourself a 1 if you can make a 10* or > angle between your upper arm and forearm (moderate to significant elbow hyperextension). Score this for both sides.
Lastly, give yourself a 1 if you can touch both palms to the floor while keeping your legs straight.
Tally up your total score out of 7. If you score a 0-2 your joints are naturally "tight" and you can greatly benefit from yoga. if you score a 3-4 you are kind of right in the middle and we'd probably need to look at your joints individually in more detail to determine which joints need more mobility and what joints need more stability. If you score a 5-7 your joints are naturally "loose" and yoga might actually increase your risk for injury. We need to do more stability work with you and very little to no stretching.
Hope this post helps some of y'all!