So you have Saul and Carrasco as the tucked in wide midfielders, Koke and Gabi in the middle, and Torres and Griezmann sitting just on top of them forcing play wide. This is how Atletico has lined up on a regular basis for several seasons now so it was no surprise to see them turning to this reliable system when facing long odds against an excellent Barcelona side at the Nou Camp.
That said, this wasn't a purely defensive, low-block 4-4-2 as Simeone has often used in the past. This is a more sophisticated team than the side that knocked Barcelona out in 2013-14. Koke is a major technical upgrade over Tiago in midfield and the Carrasco/Saul tandem on the wings actually compares quite favorably with the Arda Turan/Koke duo of two seasons ago. So Atletico would sometimes be a bit more aggressive as they squeezed Barça:
Going forward, the main thing we saw from Atletico during this stretch of play is that when attacking, Carrasco had license to surge forward and flank Griezmann with Torres working in the channel between Jordi Alba and Javier Mascherano.
The key thing this did for the Atleti is it gave them someone, Carrasco in this case, who would run directly at the Barça defense through the channels, thereby pulling multiple players out of position and creating space in the attack. Carrasco's role during this phase of play actually looks very like how Carlo Ancelotti would use Angel Di Maria to attack Barcelona two seasons ago. Here is the best example of Carrasco running at the defense:
That being said, the Catalans have faced that sort of Atletico defense many times over the past several seasons and have found ways of dealing with it. The achilles heel of Simeone's deep 4-4-2 approach is down the flanks. Atletico concedes advanced wide areas to the opposition and, if they deal with the crosses, this isn't a problem. But twice in the opening 19 minutes Barcelona's fullbacks got crosses into the box that could easily have been goals. The first came in the 13th minute cross when a Jordi Alba cross found Lionel Messi just inside the 18 yard box for a left-footed volley. Messi sprayed it badly wide, but it was a warning shot. Six minutes later a Dani Alves cross found Neymar on the edge of the six yard area. The only thing that spared Atletico in that instance was a poorly aimed header from Barcelona's prolific winger.
The problem here is relatively obvious: With Saul playing as an odd sort of right wing / right central midfield hybrid role, Juanfran doesn't have enough cover as he tries to mark Neymar down that wing. The same problem exists down the other wing for Felipe Luis and is actually even more pronounced as Carrasco is pushed further forward and the duo of Messi/Alves is more dangerous than Neymar/Alba on the left.
The result is that Dani Alves gets the ball in plenty of space and is able to pick out a perfect cross for Neymar and Juanfran simply can't keep up with the Brazilian attacker.
At that point, Simeone made a significant tactical change. From the 20th minute when the change was made until the 35th when Fernando Torres received his second yellow card, Atletico dominated the match. They had three of their seven shots, including their two best chances, during that quarter hour window and they limited Barcelona to a single, highly speculative effort from Messi from outside the box.
Here's how the Atleti looked during this window:
A few things have changed:
First, Antoine Griezmann has moved out to the right wing, which is where he often played during his time at Real Sociedad.
Second, Fernando Torres is now playing more centrally (instead of running down the right channel) as a lone striker.
Third, Saul has been pushed inside to form a midfield trio with Gabi and Koke.
Gabi has dropped off into a proper holding role behind Saul and Koke.
Defensively, the benefit here is obvious: The move to play Griezmann and Carrasco as pure wingers means they can support Juanfran and Felipe Luis on the flanks. Gabi also is given a more limited tactical brief here and is allowed to focus on anchoring the midfield and breaking up play. Essentially, Atletico put more players on the wings but still managed to keep the middle of the field congested as well.
As noted above, Barcelona, who had 21 shots over the full 90 minutes, managed only a single shot during this quarter hour and did not create a single shot inside the 18 yard box. In fact, so complete was Atletico's defensive dominance during this spell that they limited Barcelona to only one completed pass into the 18 yard box.
That said, this tactic also paid off in a big way offensively. There are two significant things this shift allowed Atletico to do when attacking. First, Atletico at times used Fernando Torres almost as a false nine as he would drop deep with Carrasco and Griezmann attacking the channels with outside-in runs from the wings. This is what led to Griezmann's chance to give Atletico a 2-0 lead in the 32nd minute:
That said, this isn't a particular innovative move. It's common for teams that have two wide forwards playing off a single striker to attack in this way.
The other tweak is more interesting. One of Simeone's greatest strengths as a manager is his ability to develop versatile, adaptable players who are comfortable in a variety of roles. Koke is his crowning achievement in this respect as the Spanish midfielder could probably play literally any midfield position in a 4-4-2, 4-3-3, or 4-2-3-1. But Saul Niguez is being developed in a very similar way. Much like Koke, he can play either a wide role in the 4-4-2 or a more central midfield role. And, like Koke, he's a technically adept player with good enough attacking instincts that one suspects he could play an advanced midfield role for a manager who likes a more conventional 4-2-3-1. This change allowed both Koke and Saul to use their versatility to full effect.
Since Gabi now held a deeper, more conservative position, it is easier for both Saul and Koke to push forward, which means Atletico now have more numbers forward when attacking and those numbers include a couple of elite creative passers. It's this change which led to the goal as Koke got into an advanced position that allowed him to play in Torres. (Also note that Saul is as far forward as Torres, which helps explain the dreadful defending from Barcelona.)
Michael Caley of Cartilage Free Captain was kind enough to pull an expected goal map for this 15 minute span of the match for me. Here's the result:
To put that dominance into context, here's the expected goal map for the whole game:
Of course, there is another question Atletico fans have to ask themselves: With Fernando Torres suspended, who will take his place in the lineup? If Simeone opts for the 4-1-4-1 system he used during their best quarter hour last week, then there are a couple ways he could go:
He could give struggling striker Luciano Vietto a chance to lead the line as a like-for-like replacement of Torres.
He could push Griezmann up top, shift Koke to the wing, and then play a midfield trio of Gabi, Saul, and Augusto, as he has recently in the league.
The trade-offs here are simple: Vietto allows Atletico to keep two proper wide forwards on the wings but is risky given Vietto's many struggles this year. Griezmann up top, meanwhile, will almost certainly offer more than Vietto, but the Koke/Carrasco wide tandem will not be as dynamic attacking the channels as the Griezmann/Carrasco duo would be.
If I had to guess, I would agree with Robbie's prediction yesterday, but Simeone is always capable of springing a surprise.