From wikipedia:
McDaniels joined the Patriots in 2001 as a personnel assistant. From 2002 to 2003, he served as a defensive coaching assistant for the team, working with the defensive backs in 2003. In 2004, he became the team's quarterbacks coach. After offensive coordinator Charlie Weis left the team following the 2004 season, the Patriots did not name an offensive coordinator for the 2005 season. According to The New York Times, in 2008, it was McDaniels who called the offensive plays for the 2005 season, although suggestions to that effect were made in 2005. After the season, McDaniels was officially promoted to offensive coordinator, while retaining his responsibilities coaching the team's quarterbacks
McDaniels and Ferentz have had pretty much identical career paths with New England...and McDaniels was calling plays in 2004 as a 28 year old and OC at 29. Brian began his Pats career as a personal assistant, then started working with tight ends although not officially a position coach, then became an official position coach...and he will be 29 next month.
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