WASHINGTON -- In the opinion of Nationals director of player development Doug Harris, outfielder Billy Burns stood out as a player who has made tremendous strides in the Minor Leagues this year.

Harris called the switch-hitting Burns a game-changer with his legs. Burns can do more than just steal bases. He hit a combined .323 with 37 RBIs, 93 runs scored, a .429 on-base percentage and 69 stolen bases.

Burns may have stepped ahead of top prospect Brian Goodwin as far as being Washington's leadoff hitter of the future. Burns could start next season with Triple-A Syracuse.

"This year, he certainly put himself in a good position," Harris said. "He has an elite skill set with the speed element. Where it goes, we shall see."

Harris is also impressed with infielder Zach Walters, who is a candidate to be a September callup. Walters was a disappointment during the first two months of the season, but with the help of Triple-A hitting coach Troy Gingrich, Walters was one of the best power hitters for Syracuse, hitting 29 home runs and driving in 76 runs.

"Troy did a good job tweaking Zack's approach, and you have seen the power blossom," Harris said. "Twenty-nine home runs, high number of doubles and he really has a better understanding of who he is and what he has to do to be successful every night."

Harris also said second baseman Danny Espinosa is showing signs of improvement at the plate. In his last 10 games, in fact, Espinosa is 12-for-44 (.273) with seven RBIs.

"He probably had some days where he was trying to find his approach, trying to find out what has worked for him," Harris said. "He has settled in nicely and has had some multiple-hit games. It looks like he is starting to get it going."

The Nationals have not decided if Espinosa will be a September callup. One baseball source familiar with Espinosa said on Thursday that Espinosa will "probably not" play for the Nats during the month of September.

Davey leaning toward starting Ohlendorf on Sunday

MIA@WSH: Ohlendorf holds Marlins to one run over five

WASHINGTON -- The Nationals have not decided who will start Sunday night's game against the Mets, but right-hander Ross Ohlendorf is the likely candidate.

After Wednesday's 4-3 victory over the Marlins, manager Davey Johnson said he was thinking about having Stephen Strasburg throw on short rest after he pitched just two innings in the rain-delayed game. On Thursday, however, Johnson said he was leaning toward Ohlendorf, which means Strasburg will start Monday against the Phillies.

Before making the final decision, Johnson wants to see Ohlendorf have two bullpen sessions. Johnson was concerned when Ohlendorf's pitches went down 10 mph in the sixth inning during Tuesday's 2-1 victory over the Marlins.

Johnson said before Thursday's 9-0 win that he could change his mind and go with Tanner Roark, but the reliever pitched two shutout innings against the Marlins.

"If I don't need Roark, I might flip flop," Johnson said before Thursday's game. "[Roark] might be the first man out today. Hopefully, Gio [Gonzalez] throws a gem and we score a bunch of runs."

Gonzalez did pitch a gem and Roark got in, but the manager didn't make an official announcement about Sunday's starter.

Worth noting

• The Marlins received a scare on Thursday afternoon. While taking batting practice, Nationals outfielder Scott Hairston hit a line drive that hit the back of right-handed reliever Ryan Webb, who was able to walk off the field. Hairston showed concern and planned to find out how Webb was doing. Miami announced the reliever sustained a bruised back.