If there is a trend to the latest turnover in the N.F.L. coaching ranks, it is hardly a new one. Veteran coaches were pushed aside or chose to retire; most of their replacements will likely be younger and expected to infuse their new teams with innovative, contemporary football strategies.
Caldwell just completed a season when the Lions were 9-7. Detroit, however, did not make the playoffs this season despite an auspicious start when they won three of their first four games.
Under Caldwell, the Lions seemed to repeatedly cower in the biggest moments, stumbling badly in late-season games with the playoffs on the line. Two of Caldwell’s Lions teams earned playoff berths but lost in the wild-card round both times.
Those failures added to a long list of postseason difficulties in the team’s history. Detroit has not won a playoff game since 1991.
Before coming to Detroit, Caldwell, 62, coached the Colts for three seasons, compiling a 26-22 record.
Fox was fired from his third N.F.L. team, although it was the first time he left with a losing record. The Bears were a troubled, losing team when Fox arrived in 2015, and he was charged with rebuilding the roster. He may have accomplished some of that — the Bears have a promising young quarterback in Mitch Trubisky — but the team played conservatively and appeared listless and overmatched.
The crowds at Bears’ home games this season grew more sparse with each defeat as the team finished last in the N.F.C. North with a 5-11 record. In three seasons, Fox, 62, had a 14-34 record.
Fox’s overall head coaching record is 133-123. In nine years with the Carolina Panthers, he made the playoffs three times and took the 2003 Panthers to the Super Bowl, where they lost by three points to the New England Patriots.
In 2011, Fox took over the Denver Broncos and led the team to four successive postseason appearances. The Broncos were routed 43-8 by the Seattle Seahawks in the Super Bowl after the 2013 season. Fox was fired one year later, with a 12-4 regular season record — and a first-round playoff loss.
Arians, 65, compiled a 49-30-1 record in Arizona. But the Cardinals, once considered a rising power, missed the playoffs the last two seasons when they were 7-8-1 and 8-8.
Pagano, 57, spent six seasons in Indianapolis but was out after the Colts this season slumped to 4-12. Del Rio, 54, lasted only three years with the Raiders, who made the playoffs last season with a 12-4 record. But this season, the Raiders (6-10) faded badly and were never in serious contention for a postseason berth.
The leading candidate to succeed Del Rio will be a popular choice among Raiders’ fans: Jon Gruden, who coached the team from 1998 to 2001 and elevated it from last place to a playoff berth. Gruden, currently an analyst for ESPN, would be the rare throwback choice in the modern N.F.L.
Gruden, 54, left Oakland to coach the Tampa Bay Buccaneers, leading them to a Super Bowl victory in 2002 over the Raiders.
Jim Schwartz, the former Lions coach, is a primary candidate to take over for the woeful Giants (3-13). Schwartz, 51, is the defensive coordinator of the Philadelphia Eagles, whose defensive unit has been a driving force in the Eagles’ dominating 2017 season. When Schwartz took over the Lions in 2009 the franchise was in disarray. Within three years, Schwartz had Detroit in the playoffs. But more losing seasons followed and Schwartz, with a 29-51 career coaching record, was fired after the 2013 season.
Schwartz, however, will not be the only coach interviewed for the Giants job. He will be competing with a host of assistants from other teams who are roughly a decade younger. These coaches are also foremost candidates for the vacant jobs in Detroit, Indianapolis, Chicago and Arizona, and conceivably in Oakland as well, if the Raiders owner, Mark Davis, cannot reach a deal with Gruden.
At the top of that list will be Patriots offensive coordinator Josh McDaniels, 41, whose work in 11 seasons with Tom Brady has been widely praised. Beginning in 2009, McDaniels spent two turbulent, rocky years as the head coach of the Denver Broncos. He was dismissed with an 11-17 record. McDaniels has been on the staff of the Patriots for each of their five Super Bowl victories.
Another prominent contender for a head coaching position this month is McDaniels’s colleague, the Patriots defensive coordinator Matt Patricia. Patricia, 43, has been coaching in a variety of roles under Bill Belichick since 2004 and took over as New England’s defensive coordinator in 2012.