Middle managers need leeway to effectively implement strategy. However, in doing so, middle managers may vary in the extent to which they diverge from top managers’ intentions, affecting implementation realization. We build on social exchange theory to examine the role of middle managers’ (MM) relational exchanges with top managers (TM), to understand how divergent strategic behavior mediates the association between TM–MM relational exchanges and implementation realization. We contribute a complementary perspective by conceptualizing middle managers as calculative agents who account for their relational exchanges with top managers in their implementation behaviors. In particular, we argue that middle managers assess the benefits and risks from their relational exchanges with TMs in strategy implementation; balancing the extent to which they facilitate the adaptability of implementation, since the required divergent strategic behaviors can enable or constrain the realization of TM's plans. Empirical evidence from 104 middle managers in a large telecommunication company mostly supports our hypotheses of a full mediation effect of middle managers’ divergent strategic behavior of facilitating adaptability, which causes their relational exchanges with top managers to indirectly shape implementation realization. These findings contribute to scholarly work on interpersonal relationships between top and middle managers during strategy implementation.