just for the record: a block is a definition of a group of elements, stored in a tablerecord, an inserted block in the drawing is called a blockreference, which is the same as an insert. attributes are stored with the reference, not in the block. try it: you can move attributes with the grips without moving the insert. if you redefine the block with the attributes in a different place, the existing attributes will stay in the old place.
so find the inserts in your drawing, check if they have atts an read their tags and values. Place then in a redim preserve variable, and compare them later on to your excel-sheet. Put the appropiate objectid in that datastructure so you can easily indentfy the right insert.