Then, Xabi Alonso left for Real Madrid, and the club finished seventh the following campaign. The deep-lying playmaker was without doubt an important part of the way they played, but it wasn't solely his move that saw them underperforming.
Faced with numerous injuries, they hadn't recruited enough quality players to deal with the on-pitch crisis. The Anfield outfit had a very good team but little strength within the squad.
The reason for this was that the owners, Tom Hicks and George Gillett, had placed a huge amount of debt on the club when acquiring it through a leveraged buyout. They needed to sell their best players and buy cheaper alternatives as a substitute.
It's a situation that Atletico Madrid fans should pay particular attention to. Three years ago the club sold David De Gea to Manchester United for a British record for a goalkeeper; his replacement has been the on-loan Thibaut Courtois.
The Belgian's superb form has meant that De Gea hasn't been missed, but it's the fact that they don't own the Chelsea stopper that should cause some concern. The De Gea money is servicing debt.
As you would expect, there are a lot of smoke and mirrors from the chief executive and majority shareholder Miguel Angel Gil Marin and from club president Enrique Cerezo. This excellent look at the club's accounts—done 18 months ago by The Swiss Ramble blog—identifies the huge problems.
Most money generated from winning either La Liga or Champions League would be used to make debt repayments. Success on the pitch means there will be little concern for all this from supporters when competing for titles, but that will change when there is a significant, and often quick, drop in performances.
For instance, at Manchester United, the chants for the removal of the Glazer family will get distinctly louder if the poor achievements continue under David Moyes.
The green-and-gold campaign that can be seen at the Vicente Calderon was taken from those in Manchester, but both clubs have seen their protests pushed under the radar.
Walking toward Old Trafford recently, many fans took no more than a little glance at the Love United, Hate Glazer headquarters before the Champions League quarter-final with Bayern Munich. I'm sure their interest will now grow as they won't even be in next season's competition.
Liverpool's Spirit of Shankly union were prominent in the removal of their former owners, with Hicks even telling Sky Sports News that their "organised internet terrorism campaign" scared off potential buyers, per the Press Association (via The Guardian).
Atleti's union are called Senales de Humo, which translates to "smoke signals." It will be a bit more difficult to remove Gil Marin and Enrique Cerezo, especially while Diego Simeone has the team performing miracles.
Atletico Madrid will need to sell at least one of their star players this summer regardless of trophies that they acquire. Their use of the third-party ownership scheme means that their transfer dealings are far from transparent.
There's a solid first 11 with a couple of a very good substitutes that can cope with one or two players leaving; however, unless they continue to unearth gems, there will be a natural decline.
Simeone has installed a work rate and mental attitude that won't leave upon the sale of one player. The problems occur when the Argentine realises it's time to move on and seek a fresh challenge.
They will probably be competing across major fronts for the foreseeable future. But they are unlikely to find themselves in such a commanding situation—Champions League semis and La Liga leaders—this late in a season for the next few years.