Wireless mesh networks (WMNs) are known for possessing good attributes such as low up-front cost, easy network maintenance, and reliable service coverage. This has largely made them to be adopted in various environments such as; school campus networks, community networking, pervasive healthcare, office and home automation, emergency rescue operations and ubiquitous wireless networks. The routing nodes are equipped with self-organized and self-configuring capabilities. However, the routing mechanisms of WMNs depend on the collaboration of all participating nodes for reliable network performance. The authors of this paper have noted that most routing algorithms proposed for WMNs in the last few years are designed with the assumption that all the participating nodes will collaboratively be involved in relaying the data packets originated from a source to a multi-hop destination. Such design approach however exposes WMNs to vulnerability such as malicious packet drop attack. This paper presents an evaluation of the effect of the black hole attack with other influential factors in WMNs. In this study, NS-3 simulator was used with AODV as the routing protocol. The results show that the packet delivery ratio and throughput of WMN under attack decreases sharply as compared to WMN free from attack. On an average, 47.41% of the transmitted data packets were dropped in presence of black hole attack.