When Buffalo running back Fred Jackson left home to bounce around the country this offseason, his NFL team blended into the weeds with all the other 6-10, sub-.500 teams. By the time Jackson got back, the Bills gained status as a popular playoff sleeper pick.

“There’s always optimism going into training camp,” Jackson said. “When you add players like Mario [Williams] and Mark [Anderson], fans get excited and we do as players. We feel like we’ve got a lot on defense.

“It’s 10 times what it normally is. The buzz around here is crazy.”

Jackson was heading for Las Vegas when he got a call that Williams, who Houston made 2006’s No. 1 overall draft pick, would be visiting Buffalo. Wanting to be there for the visit to help recruit, Jackson felt a little bit of “darn,” but soon learned it wasn’t necessary — the defensive end with 53 sacks in 82 career games had signed with Buffalo, not usually known for snagging desired free agents.

Still on the road, Jackson felt the “darn” again when he heard of Anderson’s visit. The pass-rushing ace spent 2011 with New England, rolling up 10 sacks in a pure pass-rushing role. Anderson signed a four-year deal.

Suddenly, Buffalo — which ranked 26th overall in defense, 28th in yards per play, 26th in yards per pass play and 27th in sacks per pass play — possessed a pass rush, the most important element in a modern NFL defense.

As the Bills crashed from 5-2 to 6-10, the defensive failures from early in the season could no longer be hidden. Buffalo gave up 30 points and 35 points to the Dolphins, 44 to Dallas, 37 to the Chargers and 28 to the Jets.

On offense, they resigned wide receiver Steve Johnson, got quarterback Ryan Fitzpatrick back from cracked chest bones and Jackson back from a broken leg to run with C.J. Spiller.

Jackson doesn’t mind sharing the load with Spiller, figuring everybody’s getting bigger, stronger and faster and “for a full season, that takes a toll on the body.”

The obvious AFC East favorite is the New England machine that has ruled the division the past nine seasons, winning eight AFC East titles and 11 games in the other season.

Who else in the AFC East can you like to even bother the Patriots or get a wild-card spot? In a league that has become an organized version of Bill Cosby’s Street Football routine (“…you go down to Third Street, catch the J bus. Have them open the doors at 19th Street. I’ll fake it to you…”) the Jets have risk-averse Tony Sparano as offensive coordinator working with quarterbacks Mark Sanchez and Tim Tebow.

The Dolphins are busy not saying “rebuilding” while not rebuilding a receiving corps to help their rookie head coach, Joe Philbin, and rookie quarterback, Ryan Tannehill, avoid a fourth consecutive sub-.500 season.

Besides, the Patriots suffered exactly one division loss last season — at Buffalo.

Jackson recalls that game confirming, “We can compete with anybody and everybody in the league.”