There are categories of words which never have the definite article e.g. names of countries, meals, but also uncountable nouns (like milk, rice, success etc). "Yesterday" is an uncountable noun (except in special phrases like "all our yesterdays"): you don't have more than one. If the sentence was, "...based on comments from the department's meeting," you would have to use the definite article because "department" is a countable noun. [PS success, mentioned above, can be both countable and uncountable].