VIERA, Fla., Feb. 21 -- The monotony began setting in on Felipe Lopez's spring training Wednesday morning, just the second day the Washington Nationals held a workout with the complete squad. He must keep reminding himself, as he prepares for his first full season in the District, of who he is and what he's doing. Second base. He is a second baseman.

"And then when we were doing those rundown plays," he said a couple of hours later, "I almost ran out to shortstop. I'm so used to it."

The Nationals are undergoing a defensive overhaul, and Lopez -- who has appeared in 478 major league games as a shortstop, just 12 as a second baseman -- is at the center of it. The thinking is this: Cristian Guzman, out all last season with a shoulder injury, will return to his old spot, shortstop. Lopez, who made more errors than any other National League shortstop last year, will become the regular second baseman. Fleet-footed Nook Logan will take over in center, Austin Kearns will stabilize things in right for a full season and -- poof! -- the team that was, statistically, the worst defensive squad in baseball a year ago will be transformed.

"We are going to fix that," Manager Manny Acta said. "We have to. This team, two years ago, was one of the best defensive teams in the league."

In a game sometimes ruled by numbers, defense is perhaps the hardest aspect to quantify. But the Nationals committed more errors (131) than any other team, had the worst fielding percentage (.978) in baseball and finished 29th of 30 teams in double plays turned (123).

"Let's put it this way," catcher Brian Schneider said. "It can't get any worse."

General Manager Jim Bowden believes that the defense is better than it was for most of last season simply because the personnel is different.

"I think anyone who watched this team game in and game out last season knows that it was a different defensive team in September than it was in April," Bowden said.

Keep in mind that Alfonso Soriano was new to left field last season, and though he improved dramatically over the course of the year, he committed more errors than all but one outfielder in baseball, Cincinnati's Adam Dunn. Soriano is now with the Chicago Cubs.

Jose Vidro, the primary second baseman, had become all but a statue, with range perhaps of only two steps either way. He was traded to Seattle. Nick Johnson, normally a solid fielder, had by far his worst defensive season, leading all major league first basemen with 15 errors. Though he is out indefinitely as he recovers from a broken leg, the primary candidates to replace him -- Larry Broadway and Travis Lee -- both have excellent reputations with the glove.

And on Sept. 1 of last season, the Nationals made what was, to the rest of the baseball world, a minor deal, acquiring Logan, a center fielder, from Detroit, which had cast him aside. Logan has to establish himself offensively, but there's a reason Acta said Wednesday, "If he proves to people that he can get on base, he's going to be here for a long time." It is, simply, his glove.

So the theory goes that because the Nationals who take the field Opening Day on defense will be different at six of eight positions (excluding the pitcher, with Ryan Zimmerman at third and Schneider the only returnees), they will be better.

"Automatically," Bowden said.

The statistics, to a degree, bear him out. In September of last season, after Logan arrived and with Kearns in right, Lopez at short and Vidro playing less regularly at second, the Nationals made 19 errors in 28 games -- tied for 15th in the majors, right in the middle of the pack -- and their fielding percentage rose four points to .982.

That, though, doesn't mean a direct translation to better play in 2007, particularly because Lopez must get used to a new position. Acta believes that "any shortstop who moves to second base automatically becomes better defensively," because they can now boot a ball and still have time to throw out the runner at first. Plus, he likes to use the following logic: "We have two shortstops up the middle."

Yet there is much work to be done. Not only will Acta give regular lectures to his new infield, former Cincinnati shortstop Barry Larkin -- a three-time Gold Glove winner -- will work with whomever needs help throughout the spring. Larkin knows exactly what Lopez is going through, because in 1986, Larkin's rookie season, the Reds already had a young shortstop named Kurt Stillwell. They asked Larkin to move to second base.

"I absolutely hated it," Larkin said. "Hated the idea. Didn't want to do it. I went over there and I struggled so bad that they were like: 'You know what? Never mind.' So I know: The most difficult part is mental."

Lopez, for his part, said he's comfortable making the adjustment. Though Guzman can't throw right now -- he's recovering from the aftereffects of a shot he had Monday in order to undergo an MRI exam -- he fed Lopez at second base on potential double-play balls, and vice versa.

"The real test will be in the games," Lopez said. "Once the games start, it'll come quicker. The speed will be different. Then, I'll know."

By that point, Lopez jogging out to second base might even be second nature, and the Nationals could be on their way to being a better defensive team.