يَا أَيُّهَا الرَّجُلُ!
Translation: O man!
يَا: vocative particle.
أَيُّ: addressee-form built on ḍamma in accusative position.
هَا: particle of attention.
الرَّجُلُ: nominative adjective/qualifier of “ayy”.
Al-rajulu follows “ayy” as a nominative qualifier; it is not an accusative construct vocative.