One of the major difficulties in performing post-implementation analysis for an initiative is the lack of control over the environment. Many times, multiple initiatives are being attempted simultaneously and it is difficult to attribute operational impacts to specific programs. In this paper, we examine the taxi time and departure rate impacts of two recent enhancements at Orlando International Airport (MCO): a new runway and enhanced Air Traffic Control surface surveillance through the Airport Surface Detection Equipment-Model X (ASDE-X). Both enhancements have had positive effects on surface efficiency; however, each initiative exhibits unique impact characteristics when examined in relation to the surface demand. More specifically, plots of taxi-out time and departure rate vs. surface demand show quite different behaviors. We interpret the results and believe similar analysis should be useful for refining the estimated benefits of other ASDE-X sites and predicting the impact of future surface initiatives. The suggested methodology of examining the different trend characteristics of a metric in relation to demand should provide a valuable method for future post-implementation analysis.