Oneses and Twoses
BALTIMORE (AP) — Breaking his silence on the inclusion of his name in the Mitchell Report, Baltimore Orioles second baseman Brian Roberts admitted that he used steroids once in 2003.
Brian Roberts acknowledges single use of steroids in 2003 – USATODAY.com
Brian Roberts became the poster child for the contention the Mitchell Report flung wild, unfounded accusations at possibly innocent players. Roberts frank admission therefore lends at least perceptual credibility to the findings (Roger the Dodger, you are sinking here, man).
However, is this what is being reported as a pervasive drug culture in baseball? Guys using once (Roberts) or twice (Pettitte)? I am much more concerned with systematic use. Unfortunately the Mitchell Report provides no real information on how pervasive systematic use was during the steroid era. This may end up being the greatest indictment of the Mitchell Report, that it obfuscated the real problem with a sprinkling of oneses and twoses. That, of course, is precisely the kind of soft landing MLB is hoping for.
— Michael Norton
someballyard.mlblogs.com 
Who knows how much these guys really used, but I have a hard time believing they only used once, or twice. But of course there may actually be a few guys who only used for a few weeks, felt guilty, and gave it up. So it could be these guys.
http://statisticianmagician.mlblogs.com/