We study an M-ary block-erasure channel with B blocks, where with probability e a block of L coded symbols is erased. We study the behavior of the error probability of coded systems over such channels, and show that, if the code is diversitywise maximum-distance separable, its word error probability is equal to the outage probability, which admits a very simple expression. This paper is intended to complement the error probability analysis in previous work by Lapidoth and shed some light on the design of coding schemes for nonergodic channels.