Looking at these charts, Sheets was throwing more fastballs and less breaking stuff. Zambrano was about the same as the LA outing, but his distribution of breaks is tighter.
y0 is 50 feet, five feet closer to home plate than the LA data. This results in a difference in the release point chart, and break calculations are also impacted (perhaps explaining the break distros). Someone should or may have done a study on this. Anyway.....