WASHINGTON DC, MARCH 4: Crew's Giancarlo, left, shuts off United's Fabian Espindola from the ball as the DC United play the Columbus Crew at RFK Stadium in Washington DC, March 4, 2014. (Photo by John McDonnell/The Washington Post) (John McDonnell/The Washington Post)

After gutting the roster over the winter, D.C. United entered the MLS season with a long list of uncertainties. How would the new parts take to one another and to the holdovers? Would partnerships form on the back line and front line? Who would ignite the attack?

Amid the anxiety, United was sure about one critical aspect of the team’s personality: the insatiable appetite to succeed.

While returning players were motivated to make amends for a three-win fiasco in 2013, several newcomers were determined to reaffirm their value in the league after being let go by their previous clubs. Lethargy would not become an issue.

“When you put a group of guys like that together,” captain Bobby Boswell said, “it’s pretty dangerous.”

Boswell and three teammates were claimed in MLS’s reentry draft after their contract options were declined. Others were on the outs with their respective teams.

None has expressed outright bitterness about being set free; it’s just business, they’ve said. But they all seem to be using change to stoke internal fires. Whether that renewed hunger has played a part in United’s resurgence — a five-game unbeaten streak heading into Saturday night’s match at winless Portland — cannot be proved. But it hasn’t hurt the cause.

“I know if a team didn’t pick me up and I went to another team, I would have something to prove,” Coach Ben Olsen said. “I don’t care what their motivation is. I don’t care what they use to find hunger. But it’s a necessary part of success in this league — to be hungry and have a little bit of a chip on your shoulder. Those teams tend to do a little better.”

Forward Fabian Espindola was dropped by the New York Red Bulls after last season. With United, he has recorded three goals and an assist in the past two matches, a team-best four goals overall and has become the club’s most influential attacker amid Eddie Johnson’s scoring rut.

Although Espindola scored nine goals last year — and 28 over three seasons with Real Salt Lake and then New York — the Red Bulls felt burdened by his contract.

Boswell, in his second tour in Washington after six years in Houston, has paired effectively with Jeff Parke in central defense. Sean Franklin, whose contract was not renewed by Los Angeles, has provided experience and consistency. Since conceding three goals in the opener, United (3-2-2) has yielded five in six matches.

Parke is also in his first year after he requested a trade from Philadelphia, in part for family reasons.

Johnson, the marquee offseason acquisition , wasn’t going to receive the pay raise he requested in Seattle despite leading the Sounders in goals over two seasons. So United acquired him for financial considerations and increased his salary.

Veteran attackers Davy Arnaud and Chris Rolfe also arrived via trades, while reserve defender Nana Attakora went through the reentry draft.

With the assorted pieces bonding sooner than expected, United is beginning to accumulate points.

“At the beginning of the season, everyone was all over the place,” Johnson said. “Once we got a result, we started to get the belief. . . . We’re not peaking too fast, we’re not peaking too slow — we are at a good pace but have a lot to improve.”

Soccer notes: Johnson (hamstring) and Franklin (foot) are listed as questionable on MLS’s injury report. The club declined to say whether they traveled to Portland. . . .

The Washington Spirit (2-2-0) will host the Seattle Reign (4-0-0) in a National Women’s Soccer League match at 6:30 p.m. Saturday at Maryland SoccerPlex. Seattle’s Hope Solo has conceded one goal in four starts. Diana Matheson has scored three times for the Spirit, which dropped a 3-1 decision at Seattle on April 23.