FOXBOROUGH, Mass. — Put Andre Carter at end in a 4-3 defense and quarterbacks scramble for safety. Stick him at linebacker in a 3-4 and Carter heads for a new team.

A much better player as a lineman, Carter moved to the New England Patriots this season and already has nine sacks. He can increase that Sunday against his former team, the Washington Redskins.

“Throughout my whole career, I’ve always played defensive end,” he said Wednesday. “I was just very blessed that the New England Patriots came to me and said, ‘This is what we need, this is what we’re looking for.’ And I was game.”

Carter spent his first five seasons with San Francisco, where the 49ers switched to a 3-4 alignment in his last year, 2005, under new coach Mike Nolan. The following March, Carter left as an unrestricted free agent for Washington and its 4-3 setup.

That worked well and Carter was coming off his best season with the Redskins with 11 sacks in 2009.

Then, when Mike Shanahan became coach, he installed the 3-4. That meant Carter, who had played right end most of his career, would move to left outside linebacker, where he was more involved in covering receivers than in rushing the passer.

“It was definitely a tough pill to swallow because … it was actually my second time doing the position change,” he said, “because I did it in 2005 and that’s the reason why I came to Washington in ’06 to play defensive end – the irony behind that. But you’ve got to have a sense of humor.”

Last season, Carter started just five of the 16 games he played and managed only 21⁄2 sacks. When it ended, he expected to move on. And he did after becoming an unrestricted free agent March 1.

“No sour feelings whatsoever,” he said. “It was just a mutual agreement at the end of the year. We both knew that this fit wasn’t for me and they understood that. And so we shook hands and parted ways and left on good terms.”

Shanahan called Carter “the most accountable guy you could be around” and isn’t surprised by his success with the Patriots.

“He wanted an opportunity to go someplace,” Shanahan said. “We let him go just because he was such a class guy. Obviously he landed in a great organization and he’s doing a great job for them.”

The Patriots signed him for his 11th NFL season Aug. 8 and he’s fit in well now that he’s starting again at right defensive end.

“He’s a very professional guy that’s smart, a well-conditioned athlete. He really works hard at football and things are really falling into place for him here. I know the 3-4 is probably a tough fit for him,” New England Coach Bill Belichick said, “but I think in our system in a four-man line, he fits right in. He’s really done a great job for us. I think the system is definitely part of it.”

With a long wingspan and quickness rushing from the edge, Carter has been the Patriots’ most intimidating defensive lineman. He had 81⁄2 sacks in a five-game span, including four in a 37-16 victory against the New York Jets. But he doesn’t have any in the last two games while making a total of three tackles.

But for Belichick, numbers are just part of the story.

“Statistics sometimes can be a little bit misleading,” he said. “What’s more important is their play-to-play consistency and their performance. And his have been very good. The numbers are there with it, great, but there are a lot of players that play well on a down-to-down basis that don’t necessarily have the numbers to show for it.”

The numbers for Redskins quarterback Rex Grossman aren’t very good – one of the NFL’s worst passer ratings at 69.8, at least one interception in each of the last eight games and just 10 touchdown passes in nine starts.

A quarterback who tends to throw risky passes, he has been sacked 18 times, a number Carter would like to increase.

“It takes a lot to just kind of sling it out, especially when it comes to the big plays,” Carter said, “because sometime it may be successful but at any given moment when you’re trying to win a game, you’ve got to take a shot. So that’s one thing I admire about him.”

Several Redskins who played with Carter on defense are still with the team. He credits linebacker London Fletcher with helping him adjust to that position last season.

But on Sunday, they’ll be opponents.