Modern service-oriented software applications, like those envisioned in cloud computing scenarios, operate in highly dynamic and often unpredictable environments that can degrade their quality of service. Therefore, it is increasingly important to efficiently and effectively manage the adaptation of such service compositions while guaranteeing quality attributes, such as availability, performance or cost. Within this context, software metrics to quantify the adaptability of a business process in orchestrating distributed services are highly demanded in conjunction with techniques for evaluating other system quality attributes. This paper proposes a set of software metrics to quantify the adaptability of a service-oriented application when services are composed dynamically trough a business process. The paper also proposes an approach for analyzing tradeoffs between the application adaptability and a quality of service such as availability. The feasibility of the approach is illustrated through a case study carried out with a tool we have developed.