Every NFL season brings with it a new set of daunting challenges and anxieties. Are the new free agents better than the ones who departed? How is the chemistry in the front office? Did the division get younger and faster? Is the media adversely affecting morale? Will the offensive line hold up? Is the first-round draft choice a real player or merely a weight-room freak?

X's and O's aside, it is the head coach's job to convince his players (and assistant coaches) that they can overcome those obstacles. That's pretty much it.

	Sideline personalities
	Check out Garber's breakdown on four of the NFL's coaches: Gruden: The salesman Edwards: The preacher Schottenheimer: The teacher Fassel: The scientist

When the Giants lost a handful of serviceable free agents a year ago -- including safety Sam Garnes, linebacker Jessie Armstead, tackle Lomas Brown and placekicker Morten Andersen -- a number of people who analyze the NFL for a living predicted the team would go a pedestrian 8-8.

"The team looks around and says, 'Man, I don't know if we can get this done,' " Jim Fassel said earlier this month from his East Rutherford, N.J. office. "Listen, teams have to have hope, they have to believe they can win. 'We can do this.' If they lose, they don't have that hope. It's my job to convince the team that we're going to get it right. We have a chance."

It is a subtle science, this maintenance of the team's collective psyche. Some coaches remain distant and delegate authority to their assistants and veteran leaders. Others make it a point to try to speak to every player, every day. It's all about communication and motivation, and it all comes down to a coach's particular style and personality. A coach is a teacher, a parent, a preacher, a CEO, a mechanic and, sometimes, a cheerleader.

Here are brief snapshots of four NFL coaches, at different points in their careers. Three of them prodded their teams into the playoffs last season.

Jon Gruden, who came to the Tampa Bay in a startling 11th-hour trade from the Oakland Raiders, was in his first year with the Buccaneers and took his team to the franchise's first Super Bowl victory. The Jets' Herman Edwards had already established himself with a playoff berth in his first year with the club when he had a repeat performance this past season. In his sixth season with the Giants, Fassel rallied his team to four consecutive victories to finish the regular season at 10-6 and return to the playoffs. Marty Schottenheimer, in his first season with the San Diego Chargers, fell short with an 8-8 record, but remains the NFL's leader among active coaches with 11 playoff berths in 26 seasons.

Greg Garber is a senior writer at ESPN.com.