D.C. United is enjoying a renaissance season, ascending to first place in MLS’s Eastern Conference nearing the midway point and featuring a diverse and potent attack led by the 2011 league MVP.

On all fronts, from improved defending to late-game scoring, United has made considerable strides in pursuit of its first playoff berth since 2007.

The club, however, has fallen mysteriously short in one area: attendance.

With an average of 13,668, United is 14th among 19 teams, barely ahead of Chivas USA, FC Dallas and the Columbus Crew, organizations entrenched in MLS’s lower tier for attendance for years.

It’s a glaring blemish for one of MLS’s founding teams that averaged more than 17,000 over its first 16 seasons.

This year’s count is down 10 percent from 15,196 in 2011 and is on pace to break the club’s all-time low mark of 14,532 two years ago, when United posted the worst record in team history.

The MLS average this year is 18,517, a figure elevated by Seattle’s 38,672 and Montreal’s 33,267. (The expansion Impact’s first five home games were staged inside cavernous Olympic Stadium before the club last weekend christened the renovated Saputo Stadium, which holds 20,000.)

The other 17 teams are averaging 16,382, which is a more accurate gauge of United’s place in the league.

Why, despite offering a better product, is United struggling at the gate?

The primary issue is D.C.’s schedule, which was front-loaded with home games: Nine of the first 15 were at RFK Stadium over a 2 1/2-month period. On two occasions, United played three straight home games within 10 days.

Such congested set-ups put undue pressure on marketing and ticket departments. To compound the challenge, of the nine home games, only five were played on Saturday nights, the optimal starting slot. Rain on several gamedays dampened the number of fans buying tickets on gameday, club officials said.

Why did MLS stick United with a disproportionate number of home dates so early in the season? According to the league, stadium availability was the main factor. Although United is the only full-time tenant, RFK hosts several non-MLS events, including musical and cultural festivals in the parking lots and a Howard University football game in September. Those dates are set aside when MLS begins the schedule process over the winter.

The schedule situation won’t get any better: United will play only one regular season home game between late May and early August (June 30 vs. Montreal). The club will then have four home matches at RFK in August, which is traditionally the most challenging period to sell tickets to vacationing Washingtonians. Of those four games, two are on weeknights, when crowds are noticeably smaller.

Another issue is RFK itself. Nearing its 51st birthday, the stadium doesn’t offer the amenities and game-day experiences that almost all other MLS venues now provide. United has had difficulty appealing to casual sports fans.

The club is targeting Buzzard Point in Southwest D.C., near Nationals Park, for a new stadium. However, a deal with the city and developers still appears a long way off.

This spring, by downsizing capacity for regular season matches at RFK to 19,647, United tried to alter the supply-and-demand equation and change the perception of tickets being readily available at the 45,000-seat venue. However, since attracting 16,314 for the opener, United has exceeded 15,000 just once.