BOSTON -- For perhaps the first time in decades, the most noteworthy wall around Fenway Park is not the Green Monster, but the stonewall fortress the Red Sox have built behind their pitchers.

In a 17-game stretch that started on June 11 and ended on June 30, Boston's defense went from underrated to historic.

The Red Sox did not make an error in any game during that span, becoming the first team in the history of Major League Baseball to play flawless defense for that long.

Then, the little secret the Red Sox had been admiring up close on a daily basis since the beginning of Spring Training became noticed, and so did a large reason the team led the American League East at the All-Star break.

Because it's gotten a little bit of national attention, I think [the streak] brings some notice to our team's defense, which I think is good," said Red Sox manager Terry Francona. "We show up to win. I think a good way to win is to not make errors. I just think it's brought some notice to what our team can do defensively, which is great."

For virtually the entire first half, the Red Sox have led the Major Leagues in fewest errors and fielding percentage.

When you combine a collection of vacuum-cleaner gloves with arms the caliber of Curt Schilling, Josh Beckett, Tim Wakefield, Jonathan Papelbon and Mike Timlin, the results are generally going to be good.

Schilling has even admitted to changing his pitching style a little to maximize his slick-fielding infield. By going more to his two-seam fastball, Schilling is inducing more ground balls than in recent years.

"This is the best defense I've ever seen and definitely the best defense I've ever been able to pitch in front of," Schilling said. "It's such an immense lift for a pitcher."

The strongest part of Boston's stingy "D" is the infield, which is entirely remade from last year. Chemistry issues? There are none.

"It's not like football, where you have to block for somebody," said Francona. "If the ball is hit to [Mike] Lowell, he's going to catch it, regardless of whether [Mark] Loretta [used to be] in Milwaukee. It just doesn't matter. It took the middle guys probably an hour to get to know each other."

The middle guys, as Francona refers to them, are second baseman Loretta and the glove wizard of the entire team, shortstop Alex Gonzalez. Those two, after watching each other play for years in the National League, became acquainted on the back fields of Spring Training in Fort Myers, Fla.

There doesn't seem to be a play Gonzalez can't make. Take, for example, the night of June 18, when Schilling was involved in a riveting pitching matchup with John Smoltz.

With a man on first, Edgar Renteria executed a hit-and-run by driving a ball toward the hole. Gonzalez instinctively raced to cover second, and in the instant he noticed where the ball was headed, he reversed directions, split down on one leg and somehow fired a pinpoint throw to first base for the out.

Gonzalez made a total of one error through the first three months of the season.

"Alex Gonzalez is one of the best defensive players I've ever seen," Francona said. "I've never seen some of the things that this guy has done."

Loretta doesn't wow anyone like that. He is just always in proper position, constantly making good reads and turning the double play with precision.

"What's nice is I think our pitchers have confidence in the defense," Loretta said. "You can tell the way they pitch. They're not afraid of guys putting the ball in play. That's what's gratifying to a defensive unit, is that the pitchers feel good about it."

There is no dropoff at the corners. Third baseman Lowell, last year's Gold Glover in the National League, is equally proficient at charging bunts, making a diving snag down the line or coming up with an accurate throw from wherever he releases.

RED SOX'S TOP PERFORMANCES

4/18, BOS 7, TB 4 - Adam Stern Stern makes a game-ending catch to hold off the Devil Rays, who loaded the bases to bring the go-ahead run to the plate. Highlights: 350K

5/23, BOS 5, NYY 7 - Kevin Youkilis With the Sox trailing, 1-0, Youkilis robs Jorge Posada of a hit in the second inning to prevent further damage. Highlights: 350K

5/28, BOS 5, TB 4 - Alex Gonzalez Gonzalez is in contention for an American League Gold Glove Award at shortstop because of plays like this. Highlights: 350K

6/11, BOS 5, TEX 4 - David Ortiz With two outs in the ninth, Ortiz hits a three-run walk-off homer to propel the Sox to victory. Highlights: 350K

6/29, BOS 4, NYM 2 - Coco Crisp With the Sox up by a run, Crisp robs David Wright of an extra-base hit that would have likely tied the game in the eighth. Highlights: 350K

"As a whole, I think the staff has to feel good, because we don't make extra outs," Lowell said. "I think we're eliminating a lot of the factors that cause rallies."

The unknown entering the season was Kevin Youkilis, because he was a third baseman by trade and had never played every day in the Major Leagues. All Youkilis has done at first base is save his infielders a collection of errors, making clutch scoops and also displaying some of his own fancy glovework.

"Just his work ethic, every day, he's got his routine," said third-base coach DeMarlo Hale, who doubles as an infield instructor. "He sticks with it, he works, and as he works, he's gotten better. He has a feel for the game over at first base now, as far as depth. A lot of times, depth is a key for a good defense. Sometimes, you have to give a little with certain hitters up."

The outfield got a new centerpiece this year when Coco Crisp came aboard to replace Johnny Damon. There were some questions about how Crisp would fare after being moved to left field by the Indians last season.

After flying under the radar for most of the first half, Crisp made the play of the season to date for Boston, racing to the gap in left-center on June 29 to haul in what would have been a game-tying double by David Wright of the Mets. The beauty of the play Crisp made was that the ball was actually behind him as he went into his dive.

"Under the circumstances and the time of game -- the score, everything like that -- I don't think I have seen a better play," said Francona. "That was an incredible play."

Manny Ramirez, the superstar slugger, is the one Boston defender who will never be known for his defense. Though the left fielder has met his share of blooper reels over the years, Ramirez is better than people think, particularly at Fenway, where he has mastered the angles of the Monster.

"Manny plays the wall well and has a good release," Loretta said. "It's like anything -- it's kind of contagious."

The two senior members of the Boston defense are catcher Jason Varitek and right fielder Trot Nixon, who have started at their respective positions for the Sox since 1999.

Varitek is a rock behind the plate, and Nixon seldom finishes a game without a standout play or a dirty uniform.

Just how much has the defense contributed to the solid first half put forth by the Sox?

"A lot," Francona said. "I don't know how to quantify it. I know we try to -- it's very difficult. I think it's a major plus, a strength of our ballclub. I wish I could quantify it better, [but] I don't know how to."

Perhaps the best way to quantify it is to first check out the stat sheet and then the highlight reels. They are both littered with evidence of the best defense the Red Sox have had in years, perhaps in their history.