BBZ, is right to a point, but it's also wrong imo to say that you need workhorses to go around teams pressing you. Not true. But the part I agree with is that you do need physically strong players if you play in a way that is bound to make physicality an important factor. And we have done that both with Lucho and especially with Valverde now.
It's no secret. Physically weak players are a liability in defense when used with rigid tactics and setups. The biggest problem is that we stopped playing fluid football. And by fluid, I don't mean Pep-Cruyff totaal voetbal, but any sort of positional play that involves at least medium movement from the players off the ball. It doesn't have to be as dramatic and extensive as under Guardiola.
I am amazed (not only last night) how little movement there is in the team once a teammate has the ball. It's almost no support at all. So, when the other teams have our players marked or pressed it basically comes down to that player holding on on his own in a 1 vs 1 scenario, and this, of course, means the duel is bound to have a big physical factor in it since we're not playing ballet here. It's funny because, vs Roma, the only team that played defensive destructive Italian rigid football was Barcelona. Valverde wants his players to stay in their area because he is afraid we'd lose defensive shape in transition when we lose the ball. This is defensive football at its best, with some great players who managed to influence the smaller games consistently at the right moments in the League, which is why we have this lead without playing high-quality football. This wasn't going to work with players like ours. This style works when you have the likes of Vieira in midfield, Gatusso, Nesta - Maldini - Zanetti like players in defense. These players can hold a defensive position individually in defense. Meaning if the ball is played in their area, they have the aggression, the skillset, and the tenacity to individually solve duels consistently. We don't have that. When you press our players and you manage to isolate them, they lose the ball quite a lot. Including our best players like Messi, Busquets and others.
Our players are too weak to resist high pressure in an individual way. Almost all of them. What they can do is play around that. But you need 1) speed (as in pass the ball faster than the opponent closes the channels without it) and 2) off the ball movement in order to gain space and advance the play whenever possible. Yes, Roma doing what they did automatically leaves spaces behind. You'll see that in the semifinals. But if your option is to boot the field to Messi and Suarez, you're dead. What you should do is move more off the ball, and play faster, as in every player on the ball to have a viable passing option in the first moments. Before he's tied up in an individual physical duel. So, we exposing our lack of physicality by playing a type of football that has exactly that as a key component for success. Look at all teams that defended deep (Juve early 00's, Milan mid 00's, Inter late 00's, Chelsea mid to late 00's and you'll see physical beasts in there). Players you can't just bully because they themselves are the bullying type.