My thought is that more of the "middle-level" players are taking the stuff than the big time stars. I would say bullpen guys are the #1 abusers, then sluggers, then starting pitching.
If you break down MLB into 3 categories and could group the players as the top third middle third and bottom third your curve would go way up in the middle. If I had to guess, it would look a little like this:
Top 3rd - 20% usage
Middle 3rd - 40% usage
Bottom 3rd - 10%
The top third that use are the ones that are afraid their legacy will be as a mediocre player even though they are much better then that. Some sort of a inferiority complex.
The middle third would think they can make a jump to the top 3rd and use the excuse that they are sure most of the top 3rd has to be using them to be better then they are.
The bootom third are guys that are trying to hang on and have a couple more "years in the sun".
*******The numbers are used to show a point, I don't think 23% of the league is on the juice, but I am not sure if it is higher or lower
