what roids do is help the body recover more quickly from workouts, usually by increasing testosterone levels, and protein synthesis. think about how many times you've taken a jump too deep and had to bail because of compression? you could stomp the piss out of it if you had roided out legs. same with, the bc, you can go bigger. And roids don't decrease flexibility, its the unecessary amount of muscle mas that some people choose to put on. also roids would help a ton when recovering from every little ding, and small injury that pros get during the season. Also steroids can help make you feel invincible, which translates into no fear trying new tricks, and with added muscle mass, you get injured less.
lastly, the most beneficial PED would be HGH. there is a reason Bonds liked it: because it increases strength, and increases your recovery 10x, and helps your overall well being.
Steroid would help soooooo much, but they are expensive, and most pro skiers are just scrapping by. And HGH is close to $3000 for one month, so that rules out everyone except the top pros.
Bottom line is roids will make you a better skier.