Bludging, no. He had his role and he fulfilled it. Yes he had off days like every other defender, midfielder, forward, browlow medalist, coleman medalist, premiership player. A cog or chemical element does not bludge off its counterparts...it generally remains constant and continues to do its bit (i believe he has) but things will inevitably change when you change the composition around it.
So in answer to the question posed, we still have him because maybe if those cogs were adequately replaced the machine will crank back into life. Or do we completely replace the machine?