Arnaud's bender hooked inside the upper right far post, over Seitz's head, for his fourth goal of the season.
"It is disappointing," Nowak said. "We still believe in [Seitz] and his ability to make crucial saves."
Nowak wasn't very convincing.
"It was an unnecessary goal and I think our defense made it easy for him," Nowak said. "When it comes to the crucial moments, he has to be there for the team."
Seitz admitted that he was playing more for the cross than a shot.
"I think he was at a pretty tough angle and that team is very strong in the air and it was something I was focused on," Seitz said. "I was worried about crosses and I have to raise my hand and take the blame for that."
Arnaud was just looking to put the shot on goal.
"The [free kick] was in a good spot and the coaches say from that spot to just hit the ball hard at the far post and to put the ball in a good spot where your guys can go attack it," Arnaud said. "If nobody touches [the ball,] it may have a chance to go through."
Nowak sounded as if a change could occur in goal.
"We have a system, and if it's not going to work we have to make the necessary replacements," Nowak said.
The Union (5-11-6) were going for their first MLS win streak and shutout. Kansas City (7-9-6) entered the game three points out of the eighth and final playoff spot and is now 4-1-3 in its last eight games.
Besides allowing a preventable goal, the Union failed to cash in enough offensively.
The Union dominated the first half, taking a 1-0 lead in the 33rd minute on Sebastien Le Toux's 10th goal of the season.
Justin Mapp, who continues to show an ability to attack, sent a long through ball to Danny Mwanga down the left flank. After taking two dribbles, Mwanga hit Le Toux in stride. Le Toux one-timed it in from six yards out.
"Justin gave a nice ball to Danny on the side and he gave me a perfect ball," Le Toux said. "I got one touch on it and it went in, but it was a great pass."
The Union had several chances, none better than in the 26th minute, when midfielder Stefani Miglioranzi unleashed a shot from 30 yards out that deflected off a Wizards defender and hit the left post.
Other than that, Seitz's counterpart, Jimmy Nielsen, kept the Wizards in the game with several outstanding saves, including a diving stop of a Le Toux header in the 66th minute.
Contact staff writer Marc Narducci at 856-779-3225 or mnarducci@phillynews.com.
