In this paper, an ex-ante data analysis method is developed for the assessment of the potential of improving freeway throughput by means of variable speed limits. Ex-ante evaluation of dynamic traffic management measures can provide valuable insight into the potential benefits of these measures. This information is needed when planning to implement dynamic traffic management measures. Ex-ante evaluations are usually performed by means of a simulation study. However, it is hard to reproduce realistic traffic flow characteristics in a simulation. This makes it hard to assess the potential benefits of a dynamic traffic management measure. An ex-ante data analysis, however, can provide insight into the benefits of such a measure. Therefore, a theoretical framework will be provided for analyzing the potential of jam prevention at fixed, infrastructural bottlenecks first. Then, a similar framework is developed to assess moving jam resolvability. Finally, this method is applied to off-line inductive loop detector data of the A13 freeway in the Netherlands in order to assess moving jam resolvability. It is found that approximately 18.7% of the moving jams on the A13 freeway are assessed as resolvable with variable speed limits.