With rising shares of fluctuating renewable energy generation, the role of electricity storage becomes increasingly important. However, European pumped storage plants (PSPs) are currently confronted with economic challenges and their potential for smoothing the residual load curve is consequently not fully exploited. In this paper, the long-term effects of load-smoothing and the typical price-based PSP operation are compared with an emphasis on the development of the wholesale electricity prices and the generation adequacy. The study is conducted using an agent-based simulation model of the day-ahead electricity market that has been extended by a methodology to heuristically dispatch the PSPs in Germany. The results show, that the contribution load-smoothing PSP operation can make to improving generation adequacy is rather small. Putting a strategic reserve in place reduces the differences between price-based and load-smoothing PSP operation even further. Moreover, load-smoothing PSP operation goes along with slightly increased wholesale electricity prices as compared to price-based operation.