Plenty goes into coaching: assembling a team, hiring the right assistants and game preparation, among other things.
But it is all for naught if a coach can't get the job done on gameday. Play-calling and in-game adjustments often determine the outcome of games.
Some coaches can't get it done. They wither in the spotlight. Overwhelmed by the moment, they lose track of time and forgo smarter strategy.
Here are the 20 worst in-game coaches in history.
It's been a long time since the days when Eric Mangini was known as "Man-Genius". He's been fired from his second head-coaching job in two tries at the gig.
Mangini can put together a great game plan—remember the Browns trashing the New Orleans Saints and New England Patriots this season?—but if that plan starts to become derailed, look out.
John L. Smith had success as a coach before he ended up at Michigan State. But he couldn't respond to the pressures of the biggest stage of his career.
Things came to a boil at halftime of the 2005 game against the Ohio State Buckeyes. Up 17-7 just before the half, Michigan State allowed the Buckeyes to block a field goal and return it for a touchdown after sideline chaos ended in just 10 Spartans taking the field.
Smith didn't handle the halftime television interview well and his team followed suit by not handling the second half well. The final score was Ohio State 38, Michigan State 24.
Somebody needs to commandeer Mike McCarthy's challenge flag on game days. On Sept. 27, McCarthy acted desperately in a loss to the Chicago Bears.
With over two minutes left and down three, McCarthy challenged a fumble saying he was "hopeful" that the officials would see enough to reverse the call. Hopeful enough to gamble a timeout on it with a chance still to get the ball back and tie it up.
It wasn't the first time McCarthy has caused an uproar with Packers fans for his challenge habits.
There is such a thing as too much of a good thing. When young pitchers are relied on too heavily, they flame out. Apparently, Dusty Baker hadn't learned this before managing the Chicago Cubs.
In 2003, Baker overrode Kerry Wood and Mark Prior, who pitched 211.1 and 211 innings respectively, that season. The duo combined for a 32-17 record.
But their arms couldn't hold up and went 30-32 over the next three seasons.
Dusty: you couldn't figure out how to use your relievers a little more?
Adrian Peterson carried the ball less than 20 times in 13 games the past two seasons under Brad Childress:13 out of 28 games. The best running back in the league didn't even get 20 carries in those games. What?
Childress obviously became enamored with his passing game once Brett Favre became the Minnesota Vikings quarterback. If the passing game wasn't working, Childress rarely went back to the running game to get things back on track.
One of the funniest things in the NFL the past four seasons was the Wade Phillips TV-camera cutaway. Tony Romo interception: cutaway to Wade Phillips. Missed field goal: cutaway to Wade Phillips.
Every time, it looked like somebody stole his last cookie and he was just going to pout about it instead of taking it back.
Phillips demeanor in games was detrimental to the Dallas Cowboys. There is even-keeled and then there is willing to be walked all over.
Ron Zook is one of the best recruiters in recent college football history. Steve Spurrier can thank him for bringing 5-star recruits year after year at Florida.
But bringing in talent is useless if you don't know how to use it. Zook proved while at Florida and while he's been at Illinois, that he struggles to translate talent to success on the field.
Mike Brown coached the Cavaliers to four 50-win seasons in four years as Cleveland's coach. But once the Cavs were in the playoffs, things changed.
All of the free-flow to the Cavs offense, with players spreading the ball around and using screens and plays to get open, suddenly stopped in the playoffs. Instead, LeBron James took the ball outside the three-point line and his teammates watched him.
Rumors have surfaced that James had more to do with this than Brown, but why didn't Brown just take over as head coach?
Mike Singletary was all about emotion as head coach of the San Francisco 49ers. He used passion to ignite the 49ers and San Francisco's front office made an emotionally tangled decision when they made him head coach.
But emotion can only go so far. At some point, firing players up needs to be replaced with coaching them up. Singletary never proved able to do this in games.
Ed Orgeron recruits talent as prolifically as he drinks Red Bull. He drinks a lot of Red Bull.
But in his only head coaching stint at Ole Miss from 2007-2009, Orgeron was only able to muster 10 wins.
Going 0-8 in the SEC in 2009 showed that Orgeron just couldn't get his team to execute on game days.
Herm Edwards won a lot of games in his days as head coach of the New York Jets and Kansas City Chiefs. But no team he ever coached was extraordinary.
If Edwards could have managed the final two minutes of games better, his teams may have been more successful.
After mismanaging end of game after end of game, Edwards was fired by the Jets and the Chiefs.
Rich Rodriguez has a brilliant offensive system that brings him a lot of success once he recruits the right players, which he does well.
But Rodriguez's teams don't always respond well to adversity in games. Just look to the head man. He's rarely composed, with a look of disarray or disgust on his face.
Bob Bradley has an eye for talent and usually can get players in the right formations. But he normally makes adjustments to the formation too late.
Bradley will watch as his team plays down to its opponents level until finally making a couple of moves that the television announcers have been suggesting for 30 minutes of play.
Also, there was the decision to play Ricardo Clark in the Round of 16. Clark's mistake allowed Ghana's first goal and then he was taken out in the 31st minute. Again, it was too late.
Isiah Thomas was working with the highest payroll in the NBA and led the team to the second worst record in the league in 2006.
In a game against the Denver Nuggets, Thomas instructed his team to employ a hard foul. The result was a brawl between the two teams.
Although he is 4-4 at Florida International this season, it's on the heels of a 7-25 season last year.
Despite all of the wins that Andy Reid has earned with the Philadelphia Eagles over the years, he's never truly won over the Eagles fanbase.
One reason why is his repeated offenses managing games. Even this season, the Eagles had to rely on Michael Vick's heroics after Reid's strategies left the team trailing.
There was no way for Rod Marinelli to not make this list after coaching the only team in NFL history to go 0-16.
But this isn't to pick on Marinelli's in-game coaching: His hiring, team preparation and just about everything else he touched were sub-par.
The 2008 Detroit Lions lost 11 games by more than one possession.
It's become a running joke in college football. Les Miles is prone to a few unbelievable coaching gaffes each season.
This year, it was that craziness at the end of the game against Tennessee in which the Volunteers bailed LSU out with trumping tomfoolery.
Last year, there was Miles telling his quarterback to spike the ball with only one second left in the game. That one ended in a loss.
Dutch speed skater Sven Kramer was the favorite in the 10,000 meter race in the 2010 Winter Olympics in Vancouver. Too bad Gerard Kemkers was his coach.
Kemkers surely had plenty to do with Kramer's preparation, but his instructions mid-race ended in a lane-change violation by Kramer.
Kramer was disqualified from the race.
In the 1999 NFC Championship Game, the Minnesota Vikings had the ball on their own 30-yard line with 30 seconds left with two timeouts and Randy Moss at their disposal in a tie game.
Dennis Green elected to run out the clock for overtime. Atlanta won in overtime. The Vikings were 30 yards from a decent field goal try. They could have called any pass play, whether to the sideline or over the middle.
Then, of course, there was the infamous meltdown on Monday Night Football against the Chicago Bears while Green was coaching the Arizona Cardinals.
If a team wins the overtime coin toss, it always elects to receive, considering the game is now sudden death. Somehow, along the way to becoming the head coach of an NFL team, Marty Mornhinweg didn't learn this.
He once elected for his Detroit Lions to kick in overtime. The Lions then lost on the initial overtime possession. Poor Lions fans.