Wayne Rooney believes Chris Smalling's red card "made it difficult" for Manchester United to get a positive result against Manchester City.

The centre-back received two silly bookings—one for blocking Joe Hart's goal-kick and another for a poorly attempted slide tackle—to leave his side depleted before half-time. United battled valiantly, but were eventually undone by Sergio Aguero's strike.

Rooney admitted Smalling's exit heavily influenced the tie, as told to MUTV and via Ben Jefferson of the Express:

"Chris is disappointed. It's tough when you get sent off, especially in a derby and with such a long time to go in the game it made it difficult for the rest of us to hold on. I'm sure Chris will learn from that."

Louis van Gaal appeared less optimistic and called Smalling's decisions "stupid" after the final whistle, reported by BBC Sport. Prior to the match, the manager suggested United would face an "almost impossible" task if they picked up a sending off in the derby, noted by Jefferson.

Daniel Taylor of The Guardian indicates Smalling's post-match apologies may have been wasted:

Squawka posted a breakdown of Smalling's display, compounding the player's misery:

Marcos Rojo was also forced to exit during the match after dislocating his shoulder in the second half, reported by ESPN. This leaves Van Gaal's defence in a perilous situation, as reported by Sky Sports:

United were more than a match for City before Smalling's dismissal and did well to end the fixture on the front foot. Although a quartet of penalty appeals could, and perhaps should, have gone against the visitors, it took a smart Aguero goal to separate the sides. The Etihad's overriding emotion was that of relief, not the unbridled joy you would expect from winning such an important match.

Despite the positive display, the reality is that United have 13 points from 10 matches. At this rate, Van Gaal's side will finish with 49 points, which would have landed them 10th place last season. Two losses in their last eight Premier League matches isn't disastrous, but just three wins in that time has held the team back.

Individual mistakes are costing the side. Phil Jones' decision to step up against West Brom, Robin van Persie's inability to head off the line against Chelsea and Smalling's red card are recent examples of players losing their focus for a split second. As we continue to see in the Premier League, this is often the difference between picking up three points and losing.

It's telling that, after so much outcry for new defenders during the summer, United's biggest weaknesses continue to arrive in defence. A mid-season elimination of deadwood wouldn't go amiss for players such as Smalling, who is on the verge of outstaying his welcome at the club.

Rooney's comments provide a positive spin on the situation, but United's supporters won't be so lenient on a player who continues to disappoint.