Genetic response to drugs is the most important factor after having the right genetics and shape, plenty of guys over the years have tried to overcome genetics with mgs and Ius, it just doesn't work no different to the 100m sprint, if your not naturally fast you can't be a sprinter, you need to be high 10 second 100m to be able to hit low 10s late 9s with drugs and win that medal. Drugs won't turn a guy who's a 12 second guy into Carl lewis, just like they won't turn a gym rat into Mr Olympia. They are a very important factor but only after your god given genetic base. Fertilizer will grow anything but it won't turn weeds into roses, you just get bigger weeds.