Consider this an addendum to Noel's depressingly unsurprising post on Liverpool's defensive statistics with and without Carragher over at Liverpool Offside.
The numbers speak for themselves, but I've seen multiple people (not in Noel's post, by the way) credit Liverpool's inferior record with Carragher to Liverpool having to play a deeper back line thanks to Carra's notorious lack of pace. It's become something of a pet peeve of mine, because answers usually aren't that easy.
So, using the available average position diagrams from the Daily Telegraph match reports [they're missing v QPR (without Carra), v Villa (with Carra), and at Blackburn (without), because they're the Daily Telegraph and refuse to make anything easy or sensical], I thought I'd see if that was the case.
The fullbacks seem to get forward slightly more without Carragher, especially on Carragher's side, but not incredibly significantly. All in all, the charts look relatively similar expect for the white-outlined circles denoting where Carragher was. So let's get rid of the fullbacks.
That's better. And yep, looks deeper. But, again, not as much as I expected. There's a wider range of average center-back positions without Carragher in the line-up, but more interesting than how deep they play is how close together they are. I suspect having both center-backs nearer to one another, which suggests they're working better as a unit, is more meaningful than how deep either defends.
There were two matches where Carragher played notably deeper than his defensive partner: against Bolton and Wolves. Liverpool won both. The deepest Liverpool's center-backs played came at Chelsea, without Carragher in the line-up; Skrtel's average position is nearly inside the penalty box. And yes, Liverpool won that game too. So please, let's stop the focus on how "deep" Liverpool's defense is. The above suggests that isn't the alpha or omega.
Carragher has a tendency to exacerbate multiple problems in Liverpool's defense. That he's played so often borders on the unforgivable, even if there are excuses for individual games (it's Everton, it's away from Anfield, etc, etc). But crediting problems to a single factor, such as others having to play deeper because of said lack of pace, is far too simplistic. And might not even be true. As with everything else in football, defensive positioning depends on multiple factors – the other defenders on the pitch and the opposition, most notably. Often, it's not how deep Liverpool's defense plays. Who plays may well be, though.