I don't think it's a bad idea by any means, although I could see why some super-powered people here might, particularly if their blood has unique genetic makeup. I also don't, exactly, know about blood donation in terms of health and safety standards or storage (but I'm pretty sure it doesn't hold for super long?) so that might be a bit of a speed bump, too.
Positive superpowered baseball isn't going to be anyone's undoing, though.