The U.S. National Library of Medicine brought the intensifying interest in open science to national attention when it joined enthusiastic scientists to introduce and host an Amazon-like rating forum on PubMed—the world's largest database of indexed biomedical and life sciences literature. The result was PubMed Commons. In June 2013, the commenting forum was introduced for open discussion about published scientific literature as part of a three-pronged approach to improve research rigor, reproducibility, and transparency. In Feb. 2018, the forum was unexpectedly discontinued. This retrospective explanatory case study research asked the question, "What happened on the way to the forum?" Answers came from a variety of resources using multiple methodologies for data collection and analysis. Historical data from PubMed Commons' 7,629 comments and 1,551 commenters; key informant interviews with PubMed Commons editors; and a systematized search for published articles, gray literature; and social media content about PubMed Commons were analyzed using computer-mediated discourse analysis and a social network analysis. Results from the quantitative content analysis described a forum with little participation, and the qualitative content analysis demonstrated that active forum members were focused primarily on providing links to other information resources and discussing aspects of post-publication peer review. The social network analysis revealed a disconnected network, which was supported by a sociogram showing a community of independents with only seven small clusters. Findings pointed to 11 factors that affected the forum's adoption and use. Rogers' diffusion of innovation theory scaffolds a forum innovation agility model developed from this work to offer a better understanding of organizational processes and to aid organizations interested in introducing and managing a similar forum. PubMed Commons was a missed opportunity. No comparable alternative is available to promote open science and serve as a tool for the expected paradigm shift in the way we do scholarly communication in science.