In 1988, Jon was the passing game coordinator at Southeast Missouri State.
In 1989, former Vols offensive coordinator Walt Harris took over as head coach at the University of the Pacific in Stockton, California and brought Jon in as wide receivers coach.
In 1990, Jon began his career in the National Football League when he landed a job with the San Francisco 49ers as an offensive assistant. Able to work side by side with the likes of George Seifert, Mike Holmgren and Ray Rhodes, Jon became a "West Coast Offense" man.
The following year, Jon took a one-year hiatus from the NFL to become the wide receivers coach for the University of Pittsburgh under legendary head coach Paul Hackett.
When Mike Holmgren left the 49ers in 1992 to coach the Packers, he fulfilled a promise and called upon Jon to become his offensive assistant. In 1993, Gruden was promoted to receivers coach.
After three years with Green Bay, yet another former 49ers coach called Jon. From 1995 to '97, 31 year old Jon served under Ray Rhodes with the Philadelphia Eagles as the league's youngest offensive coordinator, where he learned to deal with the egos of Randall Cunningham and Ricky Watters (practice for Keyshawn?). In his three seasons with the Eagles, his offense never finished worse than fifth in the NFC in rushing, and lead the conference in passing in 1996.