The regular season is what separates good teams from bad ones. But what separates the good teams from each other once the regular season is over?
The playoffs pit the NFL's best teams against one another, and these games are often so closely contested that the difference can sometimes come not from a player on the field, but from someone off it.
That's right, head coaches are also put in the spotlight come playoff time and their performance in these big games can make or break their careers.
So which playoff-bound coaches are best prepared to take their team to the Super Bowl and earn their paychecks?
Assuming the Rams can close out their season with a win over the Seattle Seahawks, then Spagnuolo will be making his first ever playoff appearance as a head coach.
Nobody expects St. Louis (or Seattle for that matter) to advance beyond the first round, but in all honesty it wouldn't matter who the coach is. Spagnuolo (8-23 lifetime record) is as qualified as anyone to lost to the Saints in the wild card round.
Speaking of inexperienced coaches, how about Haley who will soon complete just his second season as an NFL head coach. He's got a 14-17 career record and this will be his first appearance in the playoffs.
Winning the division was a good start.
Maybe next year Haley can work on winning a playoff game, too.
Smith was the 2008 NFL Coach of the Year after leading the Atlanta Falcons to a wild card berth in his first season.
He's got the Falcons back in the playoffs this year and will be looking for his postseason victory after winning 31 of 45 regular season games over the last three years.
Ryan spent a lot of years on the sidelines for a very successful Baltimore Ravens' franchise, but he's only in his second season as an NFL head coach (19-11 career record).
He took the Jets to the playoffs last year and made it as far as the AFC Championship game, however he's still one of the least experienced head coaches on this list.
Caldwell couldn't have asked for a better way to begin his coaching career. He led the Colts to a 14-2 record and a No. 1 seed in the AFC last season, and then took them as far as the Super Bowl where they lost to the New Orleans Saints.
The Colts have struggled this season but should still make it back to the playoffs.
Caldwell may only be in his second professional season as a head coach, but he still has something most of these other coaches don't—Super Bowl experience.
Harbaugh is in his third season as head coach of the Baltimore Ravens and in a couple of weeks he'll be making his third consecutive playoffs appearance. The Ravens are 30-14 under Harbaugh in the regular season, and 3-2 in the playoffs.
Harbaugh has a chance to improve on that record, but he'll have to get past Indianapolis in the first round.
The Packers have generally done very well with McCarthy as their head coach, compiling a 47-32 record over nearly five whole seasons.
There have been two playoff appearances in those five seasons (soon to be three if Green Bay can win this week), but unfortunately the Packers have never made it beyond the NFC Championship game.
McCarthy has a career 1-2 record in the playoffs.
Smith is one of the most well respected coaches in the NBA, and there's good reason too. He's 63-48 in his five-year career as a head coach, and has won three NFC North titles.
Smith took the 2006 Bears to the Super Bowl, but lost. Still, a 2-2 lifetime postseason record is nothing to sneeze at, and he's actually coached in a Super Bowl.
Reid has been the head coach of the Philadelphia Eagles since 1999 and has a career 118-72-1 record to show for it. In those 12 seasons the Eagles have made the playoffs nine times.
But as successful as Reid has been in the regular season, his postseason resume is not quite as impressive. Despite playing in four consecutive NFC conference championships, Reid only has a career 10-8 record in the playoffs, including a loss to the Patriots in Super Bowl XXXIX.
Payton did the unbelievable when he took the 2009 New Orleans Saints to Super Bowl XLIV and won, bringing a city devastated by Hurricane Katrina something to be happy about.
He's 48-30 in his career and will be taking the Saints to the playoffs for the third time in five seasons.
Payton's 4-1 record in the playoffs is among the best in football.
Tomlin took over for the legendary Bill Cowher in 2007 and hasn't missed a beat. The Steelers have posted a winning season each year of Tomlin's tenure, and won the Super Bowl in 2008.
Tomlin is an impressive 42-21 in the regular season and 3-1 in the playoffs.
But he still has a long way to go if he wants to match the No. 1 man on this list.
Was there ever any doubt about who would be No. 1 on this list?
Belichick is not just the best coach who will be participating in this year's playoffs, he might be the best coach ever. He has a 161-94 lifetime record as a head coach (125-50 with the Patriots) and has three Super Bowl's on his resume. He has a 15-5 career record in the playoffs.
You want big game experience? He's got it, and he's just as responsible as Tom Brady for making the Patriots once again the team to beat.