The bursty nature of traffic in metropolitan area networks results in underutilized and inefficient SONET networks. The hybrid optoelectronic ring network (HORNET) is a network being developed at the Optical Communications Research Laboratory at Stanford University to address the problems of SONET transport in metropolitan area networks (MAN's). HORNET performs packet switching using a fast-tunable wavelength transmitter, which hops to different wavelengths on a packet-by-packet basis. In this letter, we present simulation results which quantify the benefits of a wavelength tunable transmitter in a packet switched wavelength-division-multiplexed MAN. We show that a tunable transmitter is able to take advantage of imbalances in wavelength utilization, and provides a 45% improvement in packet latency characteristics. We also show that in order to maintain these benefits the tuning time of the transmitter cannot exceed 10% of the packet transmit time.