Siberian Yupik (SY) is considered a classical agglutinative polysynthetic language. Linguists often regard agglutination as more cumbersome but structurally less complicated than other morphological types. Consequently, in agglutinative languages, grammatical meanings are expected to be expressed by elements of a single level: standard morphemes. However, agglutinative morphemes occupy different ranks (orders) in the word structure, and display differences in their morphological and morphophonemic behavior. These features can be indicators of different origin and/or different time of origin for morphemes of different classes. Rank (order) analysis turns out to be “too powerful”: while designed to yield synchronic description, it “smuggles in” diachronic information. In this paper, this is illustrated by (1) a brief example of rules of the morphophonemic behavior of SY derivational suffixes, and (2) a more detailed analysis of the structure of the so-called “double tense” forms.