The play was routine, exactly the kind that Cristian Guzman is in the lineup to make. There were two outs in the bottom of the ninth inning Monday night, and the Philadelphia Phillies, trailing the Washington Nationals by four runs, had a runner on first. All that was left to do was charge the ball, field the grounder, make the throw and go home.

But Guzman couldn't do it. For an entire season in a new city, he has been scrutinized at the plate, with everyone from his manager to his hitting coach to the general manager to his teammates wondering where his stroke went, why he swings at so many bad pitches, how he can be hitting under .200 in August. Yet here was a chance to offset those struggles by making a routine, game-ending play.

"That's not focused, being focused," Nationals Manager Frank Robinson said in the hours before Tuesday night's game against the Phillies was postponed by rain (it will be made up as part of a day-night doubleheader on Thursday). "That's all that is. I really don't understand how a major league shortstop of his caliber misses ground balls like that.

"Straight at him, coming in, ball into the glove, drops out. You know, you could take a guy playing [Class] Z ball and he would at least catch that ball. That's what is puzzling me about those errors."

There has been no more puzzling character with the Nationals this summer than Guzman, the free agent shortstop who hit .266 in six seasons with Minnesota, and was then signed to a four-year, $16.8 million contract in the offseason. Every Nationals fan knows that Guzman has been a massive disappointment offensively. Following Monday's 0-for-4 night, he is hitting .188. Since 1910, only Detroit's Rob Deer (.179 in 1991) and Eddie Joost of the Boston Braves (.185 in 1943) have posted lower averages over a full season with more than 300 at-bats.

That part, however, has become virtually matter-of-fact at RFK Stadium, and if Guzman were to reach .200 -- a number he last exceeded on June 30 -- it would be looked upon as a bonus. Robinson has stuck with his shortstop in part because the potential replacement, Jamey Carroll, is a valuable and versatile bench player -- a role Robinson feels wouldn't suit Guzman well -- and in part because Guzman has fielded well.

That is, until recently. The Nationals escaped Guzman's ninth-inning gaffe on Monday, though it did lead to an unearned run and unnecessary angst. But it continued a trend of shaky fielding for the 27-year-old in recent weeks. Guzman committed eight errors through Aug. 4. In the eight games he has played since then, he has booted six balls. His 14 errors exceed, by two, his total from all of last year.

When approached about the problems Tuesday, Guzman said he didn't want to talk, a rarity for him since early in the season. Last week, in Houston, he talked about his fielding in broad terms.

"I feel comfortable," he said. "I'll be fine. I just miss a few balls. But I'm not worried about it."

Robinson, though, is clearly worried. Guzman's throws, Robinson said, have started to dive, and first baseman Nick Johnson, adept at picking low throws off the ground, has likely saved him a couple of errors recently.

"He's getting talked to about it," Robinson said. "Talked to him last night, twice, about it, and he made another throw, one Nick scooped out of the dirt, just like that. What is that?"

It is, Robinson said, a lack of focus, and it may be the same thing that is bothering Guzman at the plate. Both hitting coach Tom McCraw and former Cincinnati shortstop Barry Larkin, a special assistant to Nationals General Manager Jim Bowden, have worked with Guzman on his approach to hitting to no avail. They have tinkered with his physical approach -- Larkin has been working on the lower half of Guzman's body recently -- but the problem, as the fielding would indicate, has turned out to be more mental.

"You have to make the mental change in order to be able to hit," McCraw said. "If you make that mental change, nine out of 10 times, it will correct your physical flaws. For instance, I can tell you, 'You have a perfect batting stance,' but you swing at a curveball and you're looking for fastballs. What are you going to be? You're going to be out."

Which, in 272 of 335 at-bats, Guzman has been. The Nationals have a promising shortstop, Ian Desmond, at Class A Potomac, not to mention an athletic third base prospect, top draft pick Ryan Zimmerman, at Class AA Harrisburg. Bowden said earlier this year he felt Zimmerman would be athletic enough to play shortstop in a pinch. But neither Bowden nor Robinson is eager to promote Desmond or Zimmerman before rosters expand on Sept. 1.

Robinson was asked if the prolonged struggles at the plate have finally affected Guzman's fielding.

"Unless you're in that individual's shoes, you can't answer that," Robinson said. "Different people have gone through some similar things he's going through now, and you don't see them misplay balls like that. So it's hard to sit here and say yes or no to that."

But Robinson doesn't have to guess about one thing: If the Nationals are going to continue to win, they cannot afford to give away outs.

"A major league shortstop's got to make those plays," Robinson said. "I don't care about the balls going in the hole, and he's sitting on the grass having to make a terrific throw. To me, a major league shortstop's got to make the routine plays."

Manager Frank Robinson is watching shortstop Cristian Guzman closely: "I really don't understand how a major league shortstop of his caliber misses ground balls like that."Cristian Guzman, right, had been playing solid defense until recently. He has 14 errors this season after having 12 last year in Minnesota.