"Disadvantages" of fragmentating incoming asteroid.?

It's commonly umed that disintegrating an asteroid capable of remodeling life on Earth would make it worse because of the multiple impacts involved. What about the fact that the multiple fragments slow down more in the atmosphere, & burn up more b/4 impacting, reducing the energy of such impacts? If the object is INDEED big enough to cause a global "ELE" if it entered our atmosphere in one piece, couldn't the overall impact energy reduction offset any "cluster bomb effect"? I'm sure a cluster bomb effect can make the same amount of energy more destructive, but the further out in space the object is "articulated", the more tered the interface pattern would be, & the more likely some of the fragments will miss Earth altogether.