PHILADELPHIA (973espn.com) - When Andy Reid arrived in Philadelphia back in 1999, little was known about the former Green Bay quarterbacks coach.

What put "Big Red" over the top, however, were the relationships he was able to develop in the league and the high quality of assistant coaches he promised the Eagles would be coming along with him.

Reid ultimately delivered and if you look back at his first NFL coaching staff, it includes a host of names that ultimately turned into head coaches like John Harbaugh, Ron Rivera, Pat Shurmur, Brad Childress, Leslie Frazier and Steve Spagnuolo.

Six men from the same staff proving to be head-coaching material is an almost embarrassment of riches and doesn't even include the best assistant on the staff, the late, great defensive coordinator Jim Johnson, who suffered from a lack of ambition to rise from that position or ageism depending on who you might talk too.

The offensive chief of the staff, meanwhile, was Rod Dowhower, the final stop of what was his 35-year coaching career which included a nearly two-year stint in the big chair with Indianapolis in the mid-1980s.

In hindsight the strength of that coaching staff sent the Eagles on a path toward five NFC Championship Games over the next 10 years, unquestionably the best run of success in franchise history and the high-water mark until Doug Pederson led his team to a Super Bowl LII victory over New England earlier this month.

Pederson, of course, is another Reid acolyte who arrived as the Eagles head coach to little fanfare, the organization's Plan C only tabbed after Adam Gase chose the weather and taxes in Florida and Ben McAdoo decided to stay up the turnpike with the Giants.

In the classic example of it's better to be lucky than good sometimes, Pederson quickly lapped Gase and McAdoo as a head coach, a mentor who quickly proved to be one of the most natural and instinctive play callers ever and also a natural leader who understands the locker room due to his decade-plus spent in the league as a player.

Roseman did supplement his hire well also, particularly at the coordinator positions with veteran coaches Frank Reich and Jim Schwartz.

The Pederson tree already started branching out less than a week after the Super Bowl victory when Reich got the top spot in Indy. Meanwhile, QB coach John DeFilippo is on the fast track as the new offensive coordinator in Minnesota while few doubt that Schwartz is deserving of another opportunity.

Years from now perhaps we will look back and learn that other assistants poised for promotions like Duce Staley, Mike Groh and Press Taylor were future head coaches as well.

Either way, one of the reasons it's so difficult to win consistently in this league is the copycat nature of things. When you do win, others are waiting to loot your coaches, players and scheme.

The moving vans pulling up for Reich and DeFillippo less than a week after the Lombardi Trophy finally arrived at the NovaCare Complex is both a compliment and a curse.

The brain drain has started and the back end of this right-left combination will be free agency next month.

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen