After a fourth consecutive home loss, United Coach Ben Olsen, shown earlier this season, said, “Is my job on the line? It better be. I am the leader of this team.” (John McDonnell/THE WASHINGTON POST)

In the space of one short offseason, D.C. United has plunged from the brink of the MLS Cup final to the bottom of the league, from stout defense to crumbling resistance, from invincibility at home to booing fans.

In a performance as dreary as the wet weather, United lost its sixth straight Wednesday night, a 4-0 stinker to the Houston Dynamo before an announced crowd of 10,116 at RFK Stadium.

United (1-7-1) continued to surrender goals in the early stages, falling behind 2-0 after 28 minutes. Will Bruin had two goals and two assists for the Dynamo (6-2-2), which is 9-1-2 against United in the past 12 meetings.

Except for an encouraging spell early in the second half, D.C. displayed no chemistry, no attacking menace, no grit and no speed in being shut out for the sixth time and losing its fourth straight at home. United has conceded 12 goals in the past four matches.

The freefall has turned a harsh spotlight on Ben Olsen, a coach of the year finalist last season.

“Is my job on the line? It better be. I am the leader of this team,” he said. “But I have faith in what I am doing and I will continue to go about my work.”

The same problems, however, continue to plague United, prompting captain Dwayne De Rosario to say he was “disappointed in the lack of character right now.”

Olsen said he lit into his team at halftime, but by then it was too late.

“I still don’t get how it takes a coach to throw things and yell at you [at halftime] to now play with aggression and with the right spirit,” he said. “It’s mind-boggling to me. Maybe I will do that from the start.

“If that is what it takes to get you to play desperate and with high concentration, some guys are in trouble with just being professional athletes. Some of this has to come from within.”

De Rosario has raised his voice as well. “I have to yell to keep them motivated,” he said, “and there is only so much talking you can do.”

Eleven days after Brandon McDonald was responsible for Columbus’s three goals, the other center back was at fault against Houston. “A nightmare of a game for me,” Dejan Jakovic said. In the 16th minute, Jakovic failed to disrupt Bruin, who cruised in alone and chipped the ball over Bill Hamid for a goal.

After Bruin’s six-yard smash crashed off the crossbar, United unraveled again.

Under minimal pressure in the box, Jakovic made an ill-advised back pass to Hamid, whose rushed clearance never got airborne. Bruin intercepted and squared the ball to Giles Barnes for a simple finish from 10 yards — the ninth goal United has conceded in the first 30 minutes of matches.

“I shouldn’t have played the ball to him,” Jakovic said. “I put him in a tough situation.”

United rumbled to life after the break but couldn’t finish a number of quality opportunities.

The most agonizing were in the 63rd minute, when Houston defender Kofi Sarkodie cleared De Rosario’s consecutive shots from close range off the goal line. The first was close to crossing the line, but the second might have gone in. United’s appeals were ignored.

Bruin added his second goal in the 78th minute, despite Jakovic’s arm-tugging efforts. As Brian Ching flicked Brad Davis’s free kick, Bruin brushed off the Canadian defender for the one-timer and his eighth goal in seven regular season games against United.

Ten minutes later, Bruin crossed to Andrew Driver on a counterattack for a routine finish.

“We’re disappointed. We’re frustrated,” midfielder Perry Kitchen said. “The fans don’t deserve this. The organization doesn’t deserve this.”