Interest has been growing in alliance networks, and research has demonstrated several advantages of embedded networks, including joint problem solving. How embedded networks function as social capital and promote alliance formation has also been explored. However, less is known about constraints that they impose on firms’ extensive search for partners. In this study, we advance our understanding of the downsides of embedded networks by proposing that embedded networks facilitate alliance formations, but they may also cause suboptimal resource matching in alliance formations. Specifically, we predict that, in alliances where initial resource matching is more important than ex post collaborative activities, suboptimal resource matching is more likely when firms ally with partners with which they have pre‐existing direct or indirect ties and that such alliances decrease firm‐level resource utilization performance in operations. Using codeshare alliance data from the global airline industry, we find support for our predictions.