Sunday's tilt for D.C. United at Atlanta United was always going to be a big ask for the Black-and-Red. 

In 46 league home games since their arrival in MLS, the Five Stripes have lost just six contests. Both teams played in the middle of the week, but Atlanta was at home while United had to go on the road to dispatch FC Cincinnati, playing a day later than Atlanta. And of course, D.C. ended up being without the services of Wayne Rooney, who was rested for the game while nursing some small injuries. 

It was the first time since his arrival last July that Rooney was eligible to play in a game but did not take the field. The only other game he has missed — in all competitions — was the home game earlier this year against the Montreal Impact, for which the captain was suspended after a red card against Los Angeles FC.

For our review this week, we will take a look at how United went about confronting Atlanta without Rooney, and how much Ben Olsen might consider three center backs going forward this year. 

Luciano Acosta As The False 9

Sunday marked the third game that Rooney didn't start for United this year. Back in April, Ulises Segura got the start, a departure from the customary role the Costa Rican plays. In May, Olsen used Quincy Amarikwa and Zoltan Stieber up top in a 3-5-2 on the road against Toronto FC before Rooney came on in the second half. 

And then on Sunday, Olsen once again opted for the 3-4-2-1 formation, which was more like a 3-4-3, with Acosta taking Rooney's spot at the tip of the formation. In these three games United managed a grand total of zero goals without Rooney in the starting lineup. The Englishman — it should come as no surprise — is hugely influential in the Black-and-Red's offensive output.

Acosta was not asked to play the position the same way as Rooney, of course. And in fact, on numerous occasions, Acosta was the deepest player in the attacking trident (Lucas Rodriguez and Paul Arriola were the wingers), allowing the other two to run into open spaces with the void up top. Acosta's movement drew Atlanta defenders out in several instances, and two balls over the top from the Argentine for Arriola were the best chances that United created all game. 

D.C. will be hopeful that with just 11 games left this season, Rooney will be available to start most if not all of them. There's not much of a Plan B in attack with Rooney out of the lineup, at least one that has had much success. But if Olsen is forced into the situation again, then a front three of Acosta, Arriola, and Rodriguez might be the way to go over other potential options. 

Three Center Backs Versus Four Defenders

The game against Atlanta marked the third consecutive game in which Olsen used a three-center back system this year. In 23 league games, United's longest-serving manager has used that look on 10 different occasions. At first, the switch was made due to necessity because of the injury to Joseph Mora. But in recent weeks, Olsen has opted for the look when he could have found ways to make the 4-2-3-1 work with available personnel. 

This is significant, because in no league game in his career as a manager had Olsen used three center backs to start a game before April this year. In his previous nine seasons, Olsen had always used a back line of four defenders regardless of adjustments further up the field — whether he played one or two strikers or how he arranged his midfield.

The three-center back formation has worked this year at times for United while sputtering at others. Though the game against Atlanta ended in a 2-0 loss, for the most part the formation worked well, the second time this season United bunkered with such a formation. Of course, the late goal from Pity Martinez ruined the draw, but that defensive lapse could have happened with any system that was in use. 

With Acosta and then Rooney out, using the three-center back formation made sense for Olsen. It allowed Donovan Pines, a young, athletic center back with a crazy ability to clean up plays to get on the field. His presence allows Leonardo Jara more freedom to roam up and down the right flank, though the Argentine has stated his preference for playing in a four-man back line. 

In this weekend's trip to take on the Chicago Fire, Olsen will likely have all four of Rooney, Acosta, Arriola, and Rodriguez available. If he opts to keep the three-center back formation, one of those four players won't have a spot in the starting lineup, assuming everyone else in keeps their spot. That's the big trade-off switching from the 4-2-3-1 to the 3-4-2-1. 

Which one Olsen chooses on Saturday might be an indication of what he sees as the best option going forward for the final 11 games of the season. With the loss to Atlanta, United slipped to third in the Eastern Conference, with all seven current playoff teams bunched together. The margin of error for the Black-and-Red is decreasing, which might force the manager into making a tough decision or two in regards to which formation he utilizes.