The Red Devils were leading the Bluebirds 2-1 in the Welsh capital but conceded a late Kim Bo-Kyung goal that left them with just a point from their trip to the Cardiff City Stadium.
Barton reacted on Twitter, saying:
The ex-Manchester City midfielder also gave his verdict on the Wayne Rooney controversy that has courted attention since the draw. The striker's kick out at Jordon Mutch, which earned a yellow card, was widely viewed as being worthy of a red:
The Premier League champions have been one of the most talked about topics in world football this season as they go through a transitional period under David Moyes, named as successor to Sir Alex Ferguson's throne.
Barton highlights the club's central midfield issues as being their greatest issue, but it's hardly a secret that the club are seeking out ways to improve in that area.
Although Marouane Fellaini was brought in from Moyes' former club Everton, it's known that the club tried and failed with a raft of transfer attempts for other midfield talents, chronicled by Adam Crafton of the Daily Mail.
Among the targeted group were the likes of Cesc Fabregas, Thiago Alcantara, Sami Khedira, Daniele De Rossi, Ander Herrera and others, showing that United were and presumably are still transfixed on strengthening the middle of the park.
However, one might understand why Moyes would also have been reluctant to make moves in his first transfer window at United, preferring instead to get to grips with his squad and identify what's truly needed instead of splurging under pressure.
Barton's comments were of course also inspired by the fact that United lie in sixth place after 12 games this Premier League season and are going through their worst start to a campaign for some 25 years.
The Cardiff result was the sixth time the club have dropped points in a match this term, and one can only imagine such comments will multiply in number unless Moyes' side can develop a much stronger grip on winning matters.