Morgan stole 34 bases last year during a season in which he drew a pair of weeklong suspensions from Major League Baseball. He appealed those penalties and eventually sat out for eight games.
Last week, he was restrained by a Nationals coach as Washington scrapped with St. Louis. Morgan appeared to have upset the Cardinals by running into Albert Pujols as the star first baseman handled a tailing throw.
"It wasn't really what he didn't show as what Ankiel did show," Nationals general manager Mike Rizzo said. "Ankiel showed us he can go get the ball in the outfield. His arm is really a weapon. When he's put there, very few players are going from first to third or second to home. He can create a lot of damage with one swing of the bat.
"Nyjer had a nice spring training. After the first week he did really well. He did everything he had to do, it's just Ankiel winning the job, not Nyjer losing the job."
Morgan, who bats and throws left-handed, will back up Carlos Gomez in center field for the Brewers.
"Things can change during the season, but Carlos is our center fielder," Milwaukee manager Ron Roenicke said. "I think it adds to the depth on our bench. [Morgan] played every day last year but he'll back up Gomey. When he needs a day off, we'll have somebody to play center field."
Roenicke also said the speedy Morgan may be used as a pinch-runner because he is a "good base-stealer."
Morgan said recently that he didn't think he'd be with the Nationals on opening day.
On Saturday, manager Jim Riggleman responded: "I'm disappointed that he feels that way, but I'm sure it's based on probably him seeing two or three other guys that he is competing with."
Morgan hit .253 last year for Washington. He first was given a seven-game ban when the commissioner's office said he deliberately threw a baseball into the stands. While that was being appealed, Morgan was given an eight-game suspension on Sept. 3, two days after charging the mound against the Marlins.
Morgan eventually sat out for eight games following an appeal, rather than the original penalties of two bans totaling 15 games.
Riggleman said Morgan's difficulties last year had no bearing on what happened this spring.
"He basically had a clean slate coming in this spring and he was a model citizen," Riggleman said. "Upbeat, out there with a smile on his face. One of the hardest workers in camp."
Ankiel, who agreed to a $1.5 million, one-year contract with Washington in December, will get the majority of starts in center, while Hairston will play mainly against left-handed pitchers.
Ankiel was competing for the job in left at the start of camp, but that was locked down early on by Michael Morse.
"Before spring started they just told me to be ready to play center, left and first," Ankiel said. "You come in every day before spring, during spring, you come in to try to be that everyday guy. It's exciting."
Dykstra played third base for Wisconsin of the low Class A Midwest League last season, where he hit .312 with 39 RBIs and 27 steals. The second-round pick in 2008 also had a .416 on-base percentage.
Dykstra is expected to report on Monday and likely to join Potomac of the high Class A Carolina League.
"He's an athletic kid, he's a really good runner," Rizzo said. "He's a good offensive player with a high on-base percentage guy and works counts. He's really the type of guy that hits at the top of the lineup. Has a little pop and speed and really commands the strike zone."