I think you're overlooking the length of a rugby and football.  And, generally in this context, a discussion about size would refer more toward volume than the dimension in a single direction.  Is a golf ball the same size as a tennis ball?  Yes? No?   Well, how about the statement "a golf ball is pretty close to the same size as a speck of sand."   Their diameters differ by less than that 1.75" difference.   (diameter of a golf ball is 1.68" iigc)
I'll only do the math for the soccer ball with an 8.75" diameter.   That's conveniently 1 and 1/4 times the diameter of a soccer ball, thus the math is pretty trivial to do in the head. (5/4) The volume - the thing that really matters since density of ice is close enough to constant - is therefore 125/64 times the volume of these ice chunks.   And, even those are pretty irregular with that diameter being taken at the greatest point.   So, a soccer ball has more than twice the volume of one of those ice chunks.
So, you're saying "Well, this one has twice the volume as that one.   So, let's call it 'pretty close.'"