Edwin Jackson Sr. gave 221 / 2 years of his life to the U.S. military. He started out as the lowest-ranking cook, and by the time he retired he ran the mess hall at Fort Benning, Ga., serving three hot meals a day on a base that houses more than 100,000. He loved some of the places he lived, but when the Army told him to pack up his family and move, he did. His career carried him to Oklahoma, Louisiana, Georgia and West Germany, where his son was born.

Jackson Sr. did not know he would raise a ballplayer. Even on the day the Los Angeles Dodgers drafted Edwin Jr., he was surprised. He certainly could not have known he would raise one of the most nomadic pitchers of his generation. But when he did, his life had provided Edwin Jackson Jr. an almost cosmically ideal upbringing: A military brat grew up to become, by age 28, a journeyman right-hander.

“I used to tell him, ‘It was tough for me picking up my family,’ ” Jackson Sr. said in a phone conversation. “But it’s a job. You have to take it in stride.”

Before the Washington Nationals signed Edwin Jackson this February, he had been traded five times — six if you count his trade last year from the Chicago White Sox to the Toronto Blue Jays, who immediately dealt him to the St. Louis Cardinals. Jackson has thrown his jet-fueled fastball for six teams, none for more than two full seasons.

Jackson has been part of trades involving 22 other players, his rights shipped from the Dodgers to the Tampa Bay Rays to the Detroit Tigers to the Arizona Diamondbacks to the Chicago White Sox to the Blue Jays to the Cardinals, with whom he won the 2011 World Series. Even after making the 2009 All-Star Game, teams traded him four times. Throughout his meandering path through the major leagues, Jackson drew on his early life experiences and maintained the even-keel his father instilled in him.

“I mean, I can’t be worried about something I can’t control,” Jackson said. “I don’t have a no-trade clause. If anybody wants to trade me and that’s the route they feel is best for their organization, so be it. I’ll just say, ‘Thank you for the opportunity I had to play here,’ and take my journey somewhere else.”

The Nationals signed Jackson to a one-year, $11 million contract because they saw in Jackson what so many other teams have: a durable starter with dynamite in his right arm. His fastball averaged 94.5 mph last year, fifth fastest in the majors, according to data compiled by FanGraphs.com. And he has thrown more than 180 innings the past four seasons.

“I really don’t have an explanation for why he hasn’t found a home for more than a year or two,” said Astros General Manager Jeff Luhnow, an assistant in St. Louis when the Cardinals traded for him last year. “Sometimes, it’s just timing and what clubs need. I don’t know. He seems to have everything you need to earn a four-, five-year contract. I don’t get it. Last year, I tried to figure it out. He’s a good guy to have on the club.”

It has become a frequently asked question in baseball circles: Why does Jackson keep getting dealt? Jackson himself said he happened to fall into the right circumstances — some teams needed to shed payroll, some fell out of contention unexpectedly, some felt they could move him when his value had reached its highest point.

Jackson is the kind of pitcher that allows people to see what they want. His statistics — a 60-60 record and a 4.46 ERA — make teams think they can live without him. His raw ability makes others believe they can unlock the promise others have not. Within hours of signing Jackson, Nationals General Manager Mike Rizzo discussed tweaking Jackson’s wind-up.

Agent Scott Boras, who is notorious for not signing long-term extensions that exhaust free agent eligible seasons, represents Jackson. Knowing they would not be able to retain Jackson long-term, some teams traded him to keep from losing him down the road with nothing to show for it.

As Jackson bounced from team to team, it became easy to wonder if he had worn out his welcome. When Washington signed him, some Nationals players called friends and former teammates scattered across the league to ask about Jackson. Had they acquired a difficult personality?

Their findings could be summarized by what Adam Dunn, who played with Jackson in Arizona and Chicago, told Ryan Zimmerman: “He’s awesome.”

Jackson, by all accounts, is a hard worker, a conscientious teammate, a likeable personality. With the Cardinals, Luhnow said, he injected life into a staid clubhouse, loosening up the team by blasting hip-hop before his starts. It has not stopped nasty whispers among those who don’t know him.

“You do get a reputation,” Jackson said. “Everybody is always questioning why you’re getting traded. But I’m not here to please everybody.”

Jackson developed his laid-back demeanor by studying his father. “He made life simple,” Jackson said. The first few times Jackson was traded, Jackson’s father sensed he was upset. Jackson Sr. told his son, “I loved where I was at, but the military said you had to leave. Baseball is a business just like the Army.” Jackson quickly perked up.

Jackson lived in Germany for one year, then moved to Louisiana until he was 6, then back to Germany for two more years. He moved to Columbus, Ga., at 8, where Jackson Sr. settled and still lives.

The Dodgers drafted Jackson as an outfielder, but they quickly converted him to starting. “All I remember seeing is just him blazing 99, 100-mile per hour fastballs,” said Nationals outfielder Xavier Paul, a minor league teammate and close friend. “Just electric. He was blessed with a golden arm.”

On his 20th birthday, the Dodgers called him to the majors and sent him to the mound for his major league debut. In little more than two years, Jackson had gone from high school outfielder to pitching phenom, the No. 4 prospect in all of baseball.

“It happened so fast, man,” Jackson said. “You were in a tornado before you realized what was going on.”

His most recent offseason may have been the most hectic. After the Cardinals won the World Series, his fiancee gave birth to his first son, Exavier. Jackson will be a free agent again after this year, but he would like to settle down with his family; “anybody would,” he said. If he does not, he will know the effect it could have on his own son.

“He’ll be able to say, ‘I lived in a lot of places,’ ” Jackson said.

And Jackson can tell you, that may not be so bad.