In 2001, Zabel joined the crew of ER as an executive story editor and was promoted to co-executive producer later that season.
Zabel and R. Scott Gemmill were awarded the Humanitas Prize in the 60 minutes category in 2007 for their script for the season 12 episode "There Are No Angels Here", which followed doctors from the Chicago-set series performing aid work in a refugee camp in Darfur.
Humanitas stated that the prize was awarded for the episode's "unflinching look at the brutality inherent in civil wars and its belief that heroism is complex, complicated and multi-layered.
"[3] Zabel led the show through the 2007 Writers Guild of America Strike and picketed along with the rest of the writing team.
In 2013, he had two pilots that he wrote and produced go to series on ABC - Lucky 7 (co-written with Jason Richman) and Betrayal.