For me it's clear, he fucked up the tactics in the first half. As soon as Modric/Kroos got on the ball they released their wingers with ample space in front of them as Dest and Alba were deep in their half. Lenglet is slow as a sloth and Mingueza's positioning was suspect to say the least. Coupled with Vasquez and Mendy being unimpeded going forward the result was clear. The CDM should cover the spaces of course but we have freaking Busi there, he was barely staring to run when they were in our box lol.
Also, 3 at the back with Araujo in the middle was a very poor decision. We often had trouble getting out of our half. For 3 at the back to work you need a distributing CB in the middle and Araujo unfortunately is our worst at this. He's also slow out of the gates, wasn't really in position to help either Lenglet or Mingueza.
As soon as we changed to 4-3-3 there was suddenly Dembele putting some pressure on Mendy, Vinicius had to help more while Mingueza had help dealing with the Brazilian.
Koeman is still getting out coached by everyone worth their salt. He has to do better, has to read the opponent better from the get go.
Absolutely for me.
This is the problem with 3-4-3 and 3-5-2 imo. With a 4-3-3, the wings are done by pairs. RW/LW + RB/LB. So in this sense, fullbacks go really high up in a controlled manner, usually when the winger makes an inside run and leaves space open for an outside overlap. In moments where you have control.
But with systems where width is ensured on both ends by the fullbacks because everybody else plays narrow, everything on the wings is hugely, HUGELY dependent on the engine and the performance of the fullbacks. Fucking, hell, not even in the age of peak Alves the 3 at the back didn't work, under fucking Guardiola.
Tremendous tactical fuck-up. Here, this is before the goal.
It's simple really. Alba goes up because without fullbacks very high, you have no width in attack, Benzema goes wide to exploit the space available wide, you see Valverde picking up and pinning a defender (Lenglet), and then the Madrid fullback pushes up in space, with absolutely no-one to block him. Because well, your only wide players are caught up. Notice how huge the distance between Alba and Vazquez is.
It's naive by Koeman. 3 at the back doesn't work against team with the ability to switch the play on the wings quickly. They will find a motherload of space whenever they win a 1 vs 1 or whenever they switch the play fast.