Plus the Liverpool aggressive team unit press which is a major stress reliever for defenders, because it relieves much of the danger before it gets to them. It's like a great filter that efficiently reduces both the quantity of the attacks they need to stop, as well as their danger-factor. Which is why we played a CL final in 2009 without both the 2 best fullbacks in the world at the time arguably (Alves and Abidal), and it was barely even noticed in our defensive performance. Not because the replacements were equally great, but because the system didn't require a great deal of individual skill from these replacements. One of these replacements was 35 years old Sylvinho.
The best teams use players to integrate them into a working defensive system, either based on pressing, or based on tactical discipline and overloads, on workrate, all-around physicality, basically values that are applied to the whole compartment, or even the whole team, from attacker to the last defender. It is very rarely that players have to rely on their individual defense skills without any backing from corresponding close compartments, as it happens at Barcelona because the team values and system has vanished in the last 3-4 years.
