Straight Point recently wrote about the Fab Four for those who might be sleeping. And there has been a chorus of disapproval of their recent lack of runs.
I too am wary of statistics. What is the value of a statistical analysis? Or, even simpler, just the numbers themselves as a record of achievement? I simply don't know.
When the IPL started there was a lot of discussion about the value of numbers in evaluating performance. See the following old post by David Barry for an account of sabermetrics and cricket. Barry's excellent most recent post looks at bowlers' performance over time, asking if they get better with experience.
If a rolling five match Test bowling average is good enough for him, it's good enough for me. Here, more precisely, are graphs of each of the Fab Four's rolling 10 innings Test averages (edit: click on the images to see the full graph):

I defy anyone to pick out any kind of meaningful pattern here. For example, one might be tempted to say: "Look at Dravid's numbers over the last year...they're consistently hopeless...he ought to be dropped immediately." Well then just glance at Tendulkar's graph instead and note the low 10 innings average in 2006. Would dropping him then have been a sensible thing to do? Second guessing your way through all of this noise is a bad idea.
Here's the average of the rolling 10 innings average of the Fab Four (gulp!):
There have been very very few times that the average of the each of the Fab Four's rolling ten innings average has dipped well below 40. The last time in fact was at the tail end of 2000. That is, just after India doing very badly in Australia, before some easy Tests against Bangladesh and Zimbabwe, and then the epic battle with Australia in that series.
If there's any value at all in looking at past performances, these graphs suggest that there is no long term decline in Fab Four efforts. Let them figure out when to retire by themselves. Or am I not awake yet?