Known for liking to change his tactics up for each match, Brendan Rodgers threw something of a curve with his decision to approach Manchester United largely the same as he had the previous game against Southampton. The difference was that the second time around his decision to largely leave his fullbacks isolated in favour of overloading the midfield and allowing both Luis Suarez and Daniel Sturridge to set up as out and out strikers actually worked better than the first. Despite the final score, Southampton at times was a threat. Manchester United wasn't.
"I wanted to have superiority inside," said the manager of his decision to play the diamond for a second match in a row. "I wanted to flood numbers around the middle of the field in order to control the game. Manchester United's centre halves drop off, so we could exploit the space in front of that with Raheem's speed and then introduce Philippe to the game. We worked it the other way against Southampton, where we felt we could play through and get it into Philippe, who could open the game up, then bring Raheem into it later when it had opened up."
The one tweak is telling, as is Rodgers' reasoning behind the switch. Though Coutinho wasn't especially impressive the week before, the Brazilian playmaker is usually at his best when put under the kind of pressure Southampton likes to play with and he has the chance to beat the first man and spring Liverpool's attack. Give him space to run into, and the quality of his performances often suffers, whereas Sterling sees such space as an invitation to accelerate. Yet if the Sterling switch made tactical sense, just as important to Liverpool's success was United's failure to adjust.
Sterling had a solid afternoon, but where Liverpool won the match was behind him with the diamond's two shuttling, nominally wide midfielders—and David Moyes never adjusted his side to deal with their impact. Joe Allen and Jordan Henderson were allowed to play narrow the entire match, giving Liverpool three central midfielders against United's two. If Adnan Januzaj or Juan Mata had been able to trouble Liverpool's fullbacks it would have forced Allen and Henderson wide and left Liverpool disadvantaged in midfield, but they never really did.
The situation was exacerbated by United's fullbacks for the most part playing a defensive game, tasked with aiding United's vulnerable centre halves against Liverpool's deadly attacking trio. That meant that despite Liverpool's fullbacks being left largely isolated, they mostly faced just one attacker on the flanks, and both Januzaj and Mata had a tendency to drift inside any time United did manage to threaten the final third despite being outnumbered in their midfield build-up play. Liverpool were winning the tactical battle—and United never reacted.
"In this game, because of the pitch and the nature of Manchester United, being at home they have to attack, it would allow us to get round the back of their midfield," added Rodgers. "For a young player of 19 years of age, he is developing really well tactically, and both boys on the side—Jordan Henderson and Joe Allen—were exceptional. They very rarely get mentioned, especially Joe. But the tactical intelligence of both to play on the side of a diamond, with Steven just in behind controlling and dictating the tempo, was very good."
Moyes had options. He could have pushed his fullbacks on, attacking Liverpool's exposed flanks and perhaps forcing Rodgers to alter his tactics in response, but the United manager has always set up his teams to be hard to beat first. Yet if a proactive approach was never likely, it remains puzzling that he never tried to pull at least Mata fully inside to even up the midfield numbers. It's puzzling that even when—after 75 minutes—he did make changes, they didn't actually seem intended to alter United's basic approach to the match.
Rodgers saw a potential weakness in how he believed United would set up and seized on it, helping Liverpool to a comprehensive victory that gives fans one more reason to believe in a title challenge nobody would have bet on when the season started. For Moyes and United, on the other hand, the real concern isn't that Rodgers got it right identifying United's likeliest approach and the best way to exploit it—the real concern is that the United manager, in a display of gross incompetence, then never did anything about it.