Of all the moves the New England Patriots made in the offseason, the one that received the least amount of attention may be the one that pays off the most.

On March 17, the same day the Patriots signed cornerback Darrelle Revis and a day before they re-signed wide receiver Julian Edelman, New England signed free agent wide receiver Brandon LaFell to a three-year, $9 million contract that included a $3 million signing bonus.

After a slow start – he didn’t have a catch in the first two games – LaFell has become one of Tom Brady’s top targets, especially in the red zone.

Entering Sunday night’s game at San Diego, LaFell has set personal highs in catches (53), receiving yards (712) and touchdowns (seven). He caught two TD passes in last week’s 26-21 loss at Green Bay.

LaFell’s development has helped the Patriots become one of the most efficient offenses in the NFL.

He had only 10 catches for 165 yards and one touchdown in New England’s first four games, when the Patriots were only 2-2 and struggling, averaging just 20 points (24th in the NFL) and 298.5 yards (29th).

Now New England leads the NFL in scoring (32.4 points per game) and is seventh in total offense (385.9 yards).

Coincidence? Probably not.

Being new to the Patriots’ system – and Brady – LaFell had to earn the trust of just about everyone.

He had been a decent wide receiver with the Carolina Panthers but never had caught more than 49 passes in any of his four seasons there.

Brady said LaFell’s rise on the Patriots has been obvious. While tight end Rob Gronkowski and Edelman remain the primary targets, he gives Brady a great third option.

“When he gets a chance to make a play, he’s making them,” Brady said Nov. 23 after the Patriots beat the Detroit Lions, a game in which LaFell had nine catches for 98 yards.

“I think with new players sometimes you really don’t know what someone’s able to do in your offense until you actually get out there and do it, and you make the plays in game-type situations. Even like his run-after-the-catch ability, that doesn’t show up in training camp because we’re not tackling. And it doesn’t show up in the preseason – if he gets two catches a game it’s hard to tell.

“And then all of a sudden you see it over eight games where he’s doing it every week and it becomes a big strength for your team.”

Coach Bill Belichick has said a couple of times that the Patriots knew all along what LaFell could do, that they saw it every day in practice.

But LaFell is glad to be finally contributing after his slow start. He wasn’t even targeted for a pass in the second game of the season at Minnesota.

“It feels great to be where I’m at now compared to where I was at the beginning of the season,” he said after the Detroit game. “Going out there, putting together good games back-to-back, earning time, trust and the coaching staff’s trust. And the trust of my teammates to depend on me in big-time situations like it was today; to come to me in that situation … it feels good. But as a whole offense and as a whole team, it feels good to be in the position we are at now.”

Brady and LaFell have become especially effective at completing the back-shoulder catch – where the quarterback throws the ball behind the receiver as he stops and turns to catch it, a pass that is impossible to defend if executed correctly. That was a play missing from the Patriots’ offense the last several seasons.

“We’ve been working pretty hard at it for a while, Brandon and I,” said Brady, whose locker is next to LaFell’s. “I think it’s a big trust thing. You’ve got to trust that when the ball is in the air that they’re not going to make the play on it. And when you’re in those one-on-one situations, as a quarterback, you can only really control it until it leaves your hand.”

Brady said it helps that LaFell is 6-foot-2 and weighs 210 pounds. He’s big enough to fend off defenders while making the catch.

“When guys get tangled up with Brandon, they usually get the brunt of it,” said Brady. “The closer you are to him, sometimes I don’t think that’s the best thing because he’s such a big presence, and he’s got really long arms and he’s got big hands to be able to make those types of plays. Those are good plays for us to make … we’re going to need to keep making them, and as the season keeps going on and the games get bigger, we need to have those plays in our back pocket and know that we have confidence that we can go out there and hit them.”

Sunday is a big game for the Patriots, who stand at 9-3 after having their seven-game winning streak snapped last week. The Chargers, led by another gun-slinging quarterback in Philip Rivers, are 8-4 and in the hunt for a wild-card berth. The teams are tied with the NFL’s best record (17-3) over the final four games of the season since 2009.

If the Patriots win the rest of their games, they’ll clinch home-field advantage throughout the AFC playoffs.

“We still have a lot to play for,” said Matthew Slater, New England’s special teams ace. “We still kind of control our own destiny here, so we just have to bounce back and be mentally tough at this time and I think we’ll be able to do that.”