Breaking up a rubble pile asteroid impacter

OK, so we have a pile of rubble asteroid that is gonna hit the earth.
As it approaches, the looser rubble gets removed by the atmosphere but
most of the stuff stays together until impact making one big hole.
So, which is worse, one big hole or several smaller ones? Clearly a 1
Km sized rock is gonna ruin everyones day but if we break it up into a
bunch of 100 meter sized rocks, their surface area to volume ratio is
big and so the atmosphere burns up a lot more. Even then, the sum of
the damage done by the smaller craters is going to be less than the
damage done by a single big rock.
This is even more true considering the oceans where a big rock is
going to cause major problems whereas a bunch of smaller rocks are
not.
So, if there's gonna be an impact, I say use nukes to break it up.