The NFL regular season is over, and so are 90 percent of the college bowl games - now let the NFL coaching rumors begin! The Arizona Cardinals, Oakland Raiders, Chicago Bears, Cincinnati Bengals, Detroit Lions and Indianapolis Colts are all in the market for a new head coach, and that list could grow on Tuesday morning.

The rumor mill

The NFL coaching rumor mill is in full gear as several teams prepare to shop for a new head coach. The hottest name out there at this moment is former Super Bowl-winning coach Jon Gruden. According to an ESPN report, Gruden is expected to become the next head coach of the Oakland Raiders.

ESPN's Adam Schefter has indicated that the former head man in Oakland from 1998 to 2001 would return to the Raiders to replace Jack Del Rio, who was fired after Sunday's loss to the Los Angeles Chargers. ESPN reported Saturday that Raiders owner Mark Davis was prepared to pursue Gruden with a strong offer that could include an ownership stake in the team. If that is true, the decision for Gruden may be an easy one.

Lions coaching list growing

With Jim Caldwell getting the ax following the Lions Week 17 win over the Green Bay Packers, Detroit GM Bob Quinn made it clear why a coach who had a winning record was given his walking papers.

"We didn't beat the really good teams," Quinn said at Monday's press conference.

"Our record was above average. We're 9-7 the last two years, but our record against the better teams in the league has not been that good."

Here is another sobering way to look at it if you are a Lions fan. Detroit has beaten one playoff team in the two seasons since Quinn took over as the new general manager - and even that win had lady luck on its side.

The 14-7 victory over the Minnesota Vikings in Week 4 this season wasn't very impressive in hindsight.

The Lions had little offensive production, and one of their touchdowns came on a play in which Dalvin Cook fumbled deep in his own territory. Nevertheless, Detroit has chosen to move on from the Caldwell era and now fans in Motown want to know who will be the next man in charge of the Leo's in 2018.

With Quinn's connections to his former team, the New England Patriots, rumors are already flying that Matt Patricia (Patriots defensive coordinator) and Josh McDaniels (Patriots offensive coordinator) are at the top of the Lions list. McDaniels has a bit of head coaching experience with the Denver Broncos, however, Patricia has no experience as the man in charge. Both have had great success as coordinators.

Could the Lions be planning on promoting from within? Reports indicate that current defensive coordinator Teryl Austin is scheduled to be interviewed for the vacancy as early as Tuesday morning.

Another early rumor includes current Ravens head coach John Harbaugh. Following the Ravens meltdown Sunday against the lowly Bengals, many experts are speculating if Harbaugh will get his walking papers.

The Lions have also received permission to interview Vikings offensive coordinator and Michigan native Pat Shurmur. Shurmur coached the Cleveland Browns back in 2011 and 2012 but don't hold that against him. The current Viking OC has done wonders in Minnesota this season and has had success all across the NFL running offenses.