Chapman is a dominating left-hander, who has a 2.22 ERA with 40 strikeouts in 28 1/3 innings for New York. On Monday, he threw a fastball clocked at 105.1 miles per hour.
If the Nationals are able to acquire Chapman, that would mean Jonathan Papelbon would not be the closer. Asked how Papelbon would fit in, the source said, "He could pitch the eighth inning."
The Nationals are aware the Yankees would ask for a king's ransom for Chapman, who is a free agent after the season. The Yankees would likely be looking to replenish their farm system. Since the weekend, the Yankees have had a scout watching Washington at Nationals Park. The scout will be watching the Nationals until Sunday. The same scout recently saw the Nationals' Triple-A affiliate in Syracuse for five days.
If the Nationals are not able to land Chapman, they will have their eyes on Andrew Miller, who is having a better season that Chapman. Miller has a 1.31 ERA and has 70 strikeouts in 41 1/3 innings. Like Chapman, it would likely cost the Nationals a lot to get Miller.
On the offensive side, the Nationals are looking for a starting center fielder because Michael Taylor and Ben Revere have been inconsistent. The baseball source said to not discount the rumors that the Nationals have interest in Rockies center fielder Charlie Blackmon, who is hitting .305 with a .368 on-base percentage, though general manager Mike Rizzo said in a radio interview on Wednesday that a report regarding Blackmon "is not accurate."
The Nationals have also been linked to corner outfielders such as the Reds' Jay Bruce and the Yankees' Carlos Beltran. If the Nationals were to acquire one of those two players, it could possibly mean that Bryce Harper could move to center field. During his career, Harper has played 121 games at the position and made only five errors. However, the Nationals want to keep Harper in right.
Harper said he is willing to do anything as long as the Nationals win.
"If they want to move me [to another position] -- I love right field," Harper said. "I really don't want to move. If that's the case, you know I will do anything to win in this game. I'll do anything to win a World Series. Mike Rizzo has the best intent for this whole team. If he does anything before the Trade Deadline, it's for the betterment of the team. If I can help that, then I'm in."
Bill Ladson has covered the Nationals/Expos for MLB.com since 2002 and writes an MLBlog, All Nats All the Time. He also can be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.