anchored-transpose may be another option.
C-x t, then you can mark the first statement, press
C-x t, mark the second statement, press
C-x t, and these two statements are swapped. It seems NOT very convenient at the first sight, so it's better if you use it with other packages which can quickly mark the statements.
EDIT: I've just realized that
anchored-transpose may not be a good solution to this special case. If you quickly mark the region, you can just do a
C-w to kill the region then paste it.
anchored-transpose should fit some more general cases where there are no something like
statement, just random texts.