Delivering data in Wireless Sensor Networks (WSNs) is very challenging in that an ideal solution has to not only provide a reasonable data throughput, but also take into consideration a variety of constraints, such as battery life, computation capabilities, wireless interference, node mobility, and etc. As numerous solutions have been proposed in the past years, most designs have focused on the functionalities within a particular layer, i.e., routing protocol design in the network layer or MAC enhancements in the data link layer. However, the overall performance depends also on the interaction of mechanisms across layers. A comprehensive cross-layer performance evaluation is essential to a better understanding of the oversal system performance when deploying a new protocol. In this case study, we simulate the interaction between a more recently proposed routing protocol and a number of MAC protocols. The results show that the performance of the routing protocol varies as different MAC schemes are employed. In particular, the state-of-the-art MAC protocol might not perform the best with the routing protocl in study. No single combination dominates the other combinations in terms of all metrics in all cases.