The other Belichick associates -- some with strong ties to Belichick, others with weaker ones -- have combined for a 156-227 (.407) record as head coaches under varying circumstances, with only one posting a winning record so far. This poor mark has become a leading case against hiring Belichick assistants, but the associations could be overblown.
Matt Patricia and Mike Vrabel could find themselves in strong position to win. Patricia will inherit a 9-7 Detroit Lions team featuring Matthew Stafford and two 1,000-yard receivers. Vrabel will take over a 9-7 Tennessee Titans team that won a playoff game this season and features Marcus Mariota at quarterback.
Here's a quick look at how former Belichick assistants fared as head coaches, ordered by winning percentage. I've revisited the quarterback situations in each case and put each tenure into perspective.
The associations with Belichick are weak in some cases, especially as they pertain to whether the coaches succeeded ultimately. Josh McDaniels and Eric Mangini are two examples who spent nearly all their professional careers aligned with Belichick before becoming head coaches. Many of the others had significant careers apart from Belichick, starting with Al Groh, the only coach on the list with a winning record as a head coach.
1. Al Groh (9-7, .563)
Hired by: New York Jets, 2000
Belichick ties: Groh spent one year on Belichick's Browns staff and then became the Jets' coach when Belichick resigned after one day as Bill Parcells' successor. Groh left the Jets a year later to become head coach at Virginia, his alma mater.
QB situation: Groh inherited Vinny Testaverde and kept him in place as the starter, with Testaverde going 9-7 for a team that missed the playoffs.
Takeaway: Groh does not reflect on Belichick in a meaningful way. He had coached in both college and the NFL for two decades before spending a single season on Belichick's Browns staff. He is also eight years older than Belichick.
2. Bill O'Brien (31-33, .484)
Hired by: Houston Texans, 2014
Belichick ties: O'Brien worked on the Patriots' staff from 2007 to 2011.
QB situation: O'Brien inherited and quickly traded Matt Schaub, who had set an NFL record the previous season by throwing pick-sixes in four straight games. He went 27-21 in his first three seasons with Brock Osweiler, Ryan Fitzpatrick, Brian Hoyer, Ryan Mallett, Case Keenum, T.J. Yates, Tom Savage and Brandon Weeden as his starters. How did O'Brien do it? The Texans had the NFL's second-ranked defense over that span, according to ESPN's efficiency metric. That let O'Brien survive long enough to select Deshaun Watson in the 2017 draft.
Takeaway: O'Brien worked as a head coach at Penn State after leaving the Patriots and before joining the Texans, an experience that surely played a significant role in preparing him. He's won two AFC South titles and just earned a contract extension through 2022, putting him in position to become a success story among former Belichick assistants.
3. Eric Mangini (23-25, .479)
Hired by: New York Jets, 2006
Belichick ties: Mangini was a defensive assistant under Belichick with the Browns and Patriots, rising to defensive coordinator with New England in 2005. He also worked with Belichick on Parcells' Jets staff.
QB situation: Mangini inherited Chad Pennington, who went 11-13 as a starter during Mangini's tenure, tossing 27 touchdown passes with 25 interceptions in those starts. The team acquired Brett Favre for Mangini's final season and started 8-3, only to finish 9-7 and out of the playoffs, with Favre tossing 22 touchdowns with 22 picks.
Takeaway: Trading for Favre was part of an expensive push into the veteran player market that raised expectations for Mangini. Those expectations went unmet, and Mangini was fired. His tenure was ultimately disappointing, but not disastrous. In firing Mangini, the Jets' then-general manager Mike Tannenbaum thanked him for doing a "great job" in establishing a foundation.
4. Nick Saban (15-17, .469)
Hired by: Miami Dolphins, 2005
Belichick ties: Saban was defensive coordinator for the Browns under Belichick from 1991 until 1994.
QB situation: A.J. Feeley and Jay Fiedler were the Dolphins' notable quarterbacks before Saban arrived. The team signed Gus Frerotte in free agency before Saban's first season, then acquired Joey Harrington via trade a year later. Frerotte went 9-6 as a starter under Saban, who wound up using five starters during his tenure.
Takeaway: Saban worked as a head coach at Michigan State and LSU between leaving Belichick's Browns staff and joining the Dolphins. He was also a head coach at Toledo before joining Belichick's staff in Cleveland. Is Saban a former Belichick assistant? Yes. Did his association with Belichick define him when the Dolphins hired him? No.
5. Josh McDaniels (11-17, .393)
Hired by: Denver Broncos, 2009
Belichick ties: McDaniels had been a Patriots assistant since 2001, rising to the level of offensive coordinator before Denver hired him.
QB situation: McDaniels inherited Jay Cutler and was expected to do great things with him, but the two clashed from the beginning after Denver showed interest in former Patriots quarterback Matt Cassel, who was traded to Kansas City instead. The Broncos traded Cutler to Chicago. Kyle Orton wound up making 27 of 28 starts during the abbreviated McDaniels era, which included spending a 2010 first-round pick on Tim Tebow.
Takeaway: McDaniels' turbulent, ill-fated run with the Broncos played a leading role in bolstering the narrative that former Belichick assistants could not export New England's culture simply because they enjoyed similar autonomy. McDaniels and Mangini qualify as a Belichick protégés more than the other coaches on this list. They were relatively young and had spent nearly all their careers with Belichick when hired as head coaches.
6. Romeo Crennel (24-40, .375)
Hired by: Cleveland Browns, 2005
Belichick ties: Crennel was the Patriots' defensive coordinator under Belichick from 2001 to 2004.
QB situation: The Browns released incumbent starter Jeff Garcia shortly after hiring Crennel. The team acquired Trent Dilfer, then spent a 2007 first-round pick on Brady Quinn, but Derek Anderson and Charlie Frye were the primary starters under Crennel. Anderson went 10-5 as a starter in 2007 and earned a spot in the Pro Bowl, but the Browns missed the playoffs. They slipped to 4-12 the next season.
Takeaway: Crennel is the most recent Browns coach to win more than nine games in a season with the team. Belichick is the most recent Browns coach to win more than 10 games in a season with the team. Even Mangini's run with the Browns was better than much of what has followed; no Browns head coach since Mangini has a higher winning percentage. The Browns organization is the common denominator.
7. Jim Schwartz (29-51, .363)
Hired by: Detroit Lions, 2009
Belichick ties: Schwartz worked as a scout under Belichick with the Browns from 1993-95, but he has never coached a position or coordinated under him
QB situation: Schwartz inherited Dan Orlovsky, Jon Kitna and Daunte Culpepper from a team that had gone 0-16 the previous season. The Lions traded Kitna and drafted Matthew Stafford first overall. Stafford started 61-of-80 games under Schwartz and peaked with a 10-6 season in 2011, when Stafford ranked third in touchdown passes (41) and 13th in Total QBR (60.5).
Takeaway: A three-year scouting association with Belichick does not exactly make Schwartz a disciple, especially when we consider that Schwartz coached with Baltimore and Tennessee for more than a decade between leaving Cleveland and joining Detroit. Schwartz helped make the Lions competitive after they were historically uncompetitive. However, the team did not consistently exhibit the discipline that has long been a Belichick hallmark.
8. Eric Mangini (10-22, .313)
Hired by: Cleveland Browns, 2009
Belichick ties: See previous Mangini entry.
QB situation: Mangini inherited 2007 first-round pick Brady Quinn and named him the Week 1 starter in 2009. The team used a 2010 third-round choice for Colt McCoy. Quinn, McCoy, Derek Anderson, Seneca Wallace and Jake Delhomme each started between four and nine games for Cleveland under Mangini.
Takeaway: Mangini went 5-11 in each of his two seasons with the Browns. Cleveland has won 24 games over seven seasons since firing Mangini, an average of 3.4 victories per season. The Browns have hired four head coaches since Mangini left. Of those, only Mike Pettine has matched Mangini's winning percentage.
9. Romeo Crennel (4-15, .211)
Hired by: Kansas City Chiefs, 2011 (final three games)
Belichick ties: See previous Crennel entry.
QB situation: Crennel inherited Matt Cassel and then signed one of his former Browns quarterbacks, Brady Quinn, as a free agent before the 2012 season. Cassel and Quinn were each 1-7 as Chiefs starters under Crennel, while Kyle Orton won two of his three starts.
Takeaway: Crennel operated under dire circumstances. He took over as interim coach after Todd Haley's firing and then endured a tragic ending to his only full season in 2012 when linebacker Jovan Belcher committed suicide in the parking lot at team headquarters. Crennel's association with Belichick would not seem to rank high on a list of why his Chiefs tenure did not succeed.