original: Mark Schatz has played bass regularly with the group since 2003.
simplifications: Mark Schatz played bass often with the group since 2003. Mark Schatz played bass with the group since 2003. Mark Schatz has played bass with the group since 2003. Mark Schatz played bass on a constant basis with the group since 2003. Mark Schatz has played bass with the group since 2003. Mark Schatz has played the music instrument bass regularly with the group since 2003. Mark Schatz has played bass regularly for the group since 2003. Mark Schatz plays bass regularly in the group since 2003. Mark Schatz played bass with the group since 2003. Mark Schatz has been playing bass regularly with the band since 2003.