It depends on the sport, but it certainly helps. Humans (and all mammals) have two eyes to help them to judge distances and to see the world in three dimensions. In times gone by this would have been important when you were hunting food, or perhaps running away from something that wanted you as food (without bumping into things as you went!).
In most sports, judging distances from you is pretty important. You might need to know how far away a ball is so you can hit it successfully with your bat, or see how far away the goal is to judge how hard you need to kick. It’s quite hard to think of any sport where you don’t need to be good at working out distances for one reason or another.
When you look at the world with two eyes your brain is adding up the images that both eyes see. Because your eyes are at different positions in your face, you see things from a slightly different angle through your left and right eye. Your brain puts these signals together to tell you how far away something is.
You can see this for yourself if you put your hand in front of you with one finger pointing up, and then try and bring your other hand over your head to touch the finger. It should be quite easy with both eyes open but if you close one eye and try it again, you’ll find it much harder. This shows you that judging distances using only one eye can be quite a problem. If you have only one eye, you can practise this and get better at it, but it definitely puts you at a disadvantage compared to those with two good eyes.
Gordon Banks, who is commonly known as the best goalkeeper ever to have lived, had to cut his football career short in 1972 when he lost the sight in one eye in a car crash. Judging distance is pretty vital when you are in goal at the World Cup! Red Pollard, on the other hand, was a US jockey who famously rode the horse ‘Seabiscuit’. He lost his sight in one eye but went on to become a champion jockey. Horseracing is one of the few sports where judging distances is less important, as you have another pair of eyes on hand to help you!