D.C. United Coach Ben Olsen on Dwayne De Rosario’s suspension: ‘I just hope this is the last one we have to deal with because it affects us negatively, and we have to clean it up.’ (Patrick McDermott/Getty Images)

D.C. United will open the 2013 MLS season in almost the same way as it ended the 2012 campaign, which is both encouraging and discouraging for Coach Ben Olsen.

On the plus side, United returns the core of a roster that posted the third-highest point total in the 19-team league last season, ended a five-year playoff drought and advanced to the Eastern Conference finals.

On the flip side, the club will begin a 34-game slate on the road against Houston, which ousted D.C. from the two-game playoff series in November and denied United’s bid to return to MLS Cup for the first time in eight years. With a 3-1 loss in the first leg, United remained winless in Houston over seven seasons.

Like last year, United is not at full strength because of player petulance. As expected, MLS on Friday suspended star attacker Dwayne De Rosario for two matches and fined him an undisclosed amount for head-butting an opponent in the preseason finale last weekend. He also will miss the March 9 home opener against Real Salt Lake.

United had been bracing for bad news, having received indications early in the week that De Rosario would probably have to sit out two games. Commissioner Don Garber denied De Rosario’s appeal late Thursday.

“I would love to defend Dwayne or my players, but this one, I can’t necessarily do that,” Olsen said. “I just hope this is the last one we have to deal with because it affects us negatively, and we have to clean it up.”

Olsen is particularly sensitive to suspensions. In the playoff opener last year against New York, Andy Najar was ejected for tossing the ball at the referee and subsequently banned three games overall (one automatically for receiving a red card and two additional matches by the disciplinary committee).

Najar’s absence, combined with leading scorer Chris Pontius’s groin ailment and De Rosario’s knee injury, left United at a notable disadvantage against the disciplined, experienced Dynamo.

De Rosario has declined to comment on the latest matter, a 59th-minute red card for head-butting Philadelphia Union midfielder Danny Cruz on the nose during a multi-player scuffle at the Disney Pro Soccer Classic. The outburst was out of character for De Rosario, who has received just two red cards (both in 2006) in 324 regular season and playoff appearances.

In announcing the suspension, MLS said the United captain used “violent conduct that endangered the safety of the opponent.”

A suspension for preseason misconduct is not unprecedented. Ten years ago, United’s Hristo Stoitchkov was banned for two games and fined for a tackle that broke an American University player’s leg.

Despite De Rosario’s suspension, United players and coaches say they believe chemistry and experience will carry them a long way. The club showed its grit late last year without the injured De Rosario, going 5-0-2 down the stretch and beating the New York Red Bulls in the playoffs.

“The most successful teams are the ones with the guys who have been around together for a while – it’s a major part in the success we will have this year,” defender Brandon McDonald said. “We are still getting to know each other but you can sense it growing.”

United is not exactly the same: Najar was sold to Belgian club Anderlecht and the club cut ties with defender Emiliano Dudar (10 starts) and attackers Branko Boskovic (seven assists), Hamdi Salihi (six goals) and Maicon Santos (seven goals).

Nonetheless, “We still have our spine,” McDonald said. “If we can stay healthy, a lot of good things will come out of the year.”

The spine includes several young players poised for big years: Pontius, an all-league selection last year; goalkeeper Bill Hamid, a U.S. national team candidate; and midfielders Perry Kitchen and Nick DeLeon, who were among MLS’s top rookies in 2011 and ’12 respectively.

Last year’s experience helped United “understand the grind it takes to get to the playoffs and understand the grind it takes to get through the playoffs,” Hamid said. “We fell short, but we have more sense of how to go about things in both situations.”

United bolstered depth by acquiring Brazilian forward Rafael, 20; Guatemalan forward Carlos Ruiz, 33, MLS’s third-highest active scorer; veteran midfielder John Thorrington, 33; Panamanian national team midfielder Marcos Sanchez, 23; and James Riley, 30, who might start at right back.

“We hope we are ahead of the curve because of the familiarity we have with each other,” Olsen said. “I thought last year we were organized and committed, and that is what got us to where we needed to be. If we don’t have those things, the chemistry doesn’t matter so much.”