A variety of applications can include apparatus and/or methods to preemptively detect defect prone memory blocks in a memory device and handle these memory blocks before they fail and trigger a data loss event. Metrics based on memory operations can be used to facililtate the examination of the memory blocks. One or more metrics associated with a memory operation on a block of memory can be tracked and a Z-score for each metric can be generated. In response to a comparison of a Z-score for a metric to a Z-score threshold for the metric, operations can be performed to control possible retirement of the memory block beginning with the comparison. Additional apparatus, systems, and methods are disclosed.