I completely agree with Dews. I bet it's safe to assume that easily more then 35% of players in the MLB have used something illegal in the past 2-3 years. Just listen to the interview with the Balco president after this latest incident with Melky Cabrera. The guy states that you have to be an idiot to get caught now-a-days with all of the masking that is done with these designer drugs. Hell, a lot of these drugs don't even have tests to detect them because they are so new. I'd also be willing to bet that over 75% of the illegal drug use in baseball isn't your sterotypical "steroids" but more along the lines of cutting edge HGH-type drugs that are there to improve your energy and ability to heal. On a day-to-day basis, they don't "jack" you up like steroids do so it isn't noticeable and you have the energy and durability to get at your best every single game, alongside all of the other preparation professional athletes do - exercise, weight lifting, eating properly, etc.
Baseball is crooked, it has for hundreds of years, and a few years of steroid and HGH testing isn't going to change that. The designer drug industry is just too current and too good at masking that it's almost impossible for the testing to keep up.