New England Patriots On March 14, 1973, Erhardt moved on to become backfield coach of the
New England Patriots, a post he served in for four years before being promoted to offensive coordinator on February 1, 1977, following the departure of
Red Miller. After missing the playoffs that year, the Patriots seemed ready to challenge for a
Super Bowl berth in 1978. However, prior to the last regular season game on December 18, head coach
Chuck Fairbanks announced he was leaving the team to accept a contract offer from the
University of Colorado. In response, the team suspended Fairbanks and made Erhardt and fellow assistant
Hank Bullough co-coaches for the final game. The Patriots dropped that contest, then lost their opening round matchup to the
Houston Oilers. Fairbanks was allowed to leave for Colorado, with Erhardt officially taking the reins of the team on April 6, 1979. Noting his .890 winning percentage at North Dakota State upon taking the position, Erhardt said, "I've never been a loser in football and I don't intend to start now." The Patriots underachieved to a 19–13 record in the 1979 and 1980 seasons, missing the playoffs by one game each year; the 441 points scored in 1980 was a club record not broken until 2007. But then the Patriots finished with a 2–14 record in 1981. Citing the fact that Erhardt "was just too nice a guy", owner
Billy Sullivan dismissed him on December 22, two days after the conclusion of the season.
New York Giants Just over a month later, in January 1982, Erhardt was hired as offensive coordinator of the
New York Giants by head coach, and former fellow Patriots assistant
Ray Perkins, the first since
Joe Walton filled the position under head coach
Alex Webster in 1973. During the latter portion of that first season, Perkins announced he was leaving to become head coach at the
University of Alabama, with
Bill Parcells replacing him. Parcells had been Erhardt's linebackers coach with the Patriots in 1980, and kept his former boss in the same position. That decision would prove to be the right one as the Giants went on to win two
Super Bowls, with Erhardt working around a key injury during the run toward
Super Bowl XXV. Quarterback
Phil Simms had suffered a season-ending injury late in the season, but his replacement,
Jeff Hostetler, navigated the team to the title. Parcells retired after that game, with
Ray Handley being promoted to head coach. Erhardt was moved to assistant coach for the 1991 season with diminished responsibilities as Handley served as his own offensive coordinator. On January 7, 1992, Erhardt was dismissed by Handley.
Pittsburgh Steelers Handley then demoted Erhardt, which resulted in the latter's departure for a similar position with the Pittsburgh Steelers in 1992. Emphasizing the run, Erhardt ran the offense for four years, helping the team reach
Super Bowl XXX in 1996. However, after the season, the conflict over the offensive philosophy between Erhardt and Steelers' head coach
Bill Cowher resulted in Erhardt's contract not being renewed, which was announced on January 31, 1996.
New York Jets Erhardt then became offensive coordinator of the
New York Jets under
Rich Kotite. A disastrous 1–15 mark marked the end of Kotite's brief era, with Parcells replacing Kotite. In the 1997 season, Erhardt was stripped of his playcalling duties while serving as just quarterbacks coach. Erhardt announced his retirement on January 12, 1998. ==Head coaching record==