FOXBORO — Just as hitting the 10-year mark as a player in the NFL is a difficult and not-so-common achievement, the same can be said for head coaches in the league.

This season marks Bill Belichick’s 10th at the helm of the New England Patriots, and of the 31 other teams in the league, only two have been with their team longer: the Titans’ Jeff Fisher and the Eagles’ Andy Reid.

But in a league that changes every year — witness the NFC’s run of sending eight different teams to the last eight Super Bowls — Belichick has had to alter and adapt his team to keep it at a high level under his stewardship.

Kevin Faulk is now one of only two players who have been with the Patriots longer than Belichick (Tedy Bruschi is the other), and he has seen the evolution of his head coach in that time.

Not surprisingly, the running back notices differences in Belichick.

“The first year he got here, it was just about letting the guys know where he was, what he stood for and what type of football team that was. Being here at that time meant he had to make a lot of people unhappy,” Faulk said. “But at the same time as you went through that process you understood what he was doing. Being here as long as I have and being with him, you understand exactly where he is and what he’s doing, and that’s trying to build a team each and every training camp. That’s what he wants.”

On the outside, Belichick is seen as an unsmiling taskmaster, a man who has no issues with getting in his players’ faces and chewing them out for the smallest transgressions.

Make no mistake — he wants things done the right way, but he’s not quite as steely as the gray of his beloved hoodie.

Fred Taylor expected Belichick to be like one of his former coaches with Jacksonville, current Giants coach Tom Coughlin, but has discovered that he’s not quite as difficult to please.

“Before I got here, knowing that this is a team that has achieved championship status … usually your coach has to be a little off-track if you’re going to be one of those teams that is always winning,” Taylor said. “Kind of like coach Coughlin, I kind of pictured them in the same mode a little bit. (Belichick) is very passionate. He’s very detail-oriented, but he’s a little more loose than coach Coughlin was.

“The perception before I got here was that he was just a hardball, tough, no-nonsense (coach), and he has his — every coach has their moments — but I think it will be a little easier to play for him than it was to play for coach Coughlin. He’s not has hardball as I initially thought. Still hard, though.”

Receiver Greg Lewis, who played for Reid in Philadelphia, also mentioned Belichick’s passion for the game of football.

That passion has not waned for Belichick despite being his 35th NFL season.

On Thursday, he said the first day of training camp still excites him, and that despite all of the hours and demands of his job, he doesn’t really consider it work.

“I come to work with an energy every day, whatever it is,” Belichick said. “Whether it’s the team building that goes into the draft and free agency, or the passing camps, rookie mini-camp, working with the young players, the game-planning, game preparation we put in during the fall months … of course, any games are always thrilling, and game day itself. I certainly enjoy the game competition. I enjoy the whole spectrum of it.”

Belichick may not readily be classified as a “player’s coach,” but Wes Welker has figured out a trick to stay on his good side.

“My perception was that he was definitely a [tough] guy and kind of on you all the time. He’s definitely that,” Welker said. “He can be very easygoing, too. As long as you prove to him that you handle your business and you work hard and you take care of everything you need to take care of, then he’s a lot more easygoing with you. You just have to continue to do those things and make sure that he trusts you, then things are usually a lot smoother with him.”

As for Belichick, he knows he’s changed a bit, too, after a decade with New England.

“I’d say I’m a lot friendlier,” he deadpanned, then broke into a grin.

smanza@projo.com