In a recent article, Aichert and Ziegler (2004) explore whether apraxia of speech (AOS) can be explained by disruption of the phonetic plans for high frequency syllables. This approach is a hybrid one, combining the notion of a mental syllabary with an explanation that the impairment in AOS results from reduced access to supra-segmental phonetic plans. In this commentary, we explore Aichert and Ziegler's approach and suggest that in testing a hybrid model it is important to be cautious in identifying implications for the two source models.