xAI has lost three key developers responsible for its Grok model within a week, amid delays in releasing new model versions. Tianyi Zhang, Juntang Zhuang, and David Haxton, who led Grok's search, pre-training, and voice product lines respectively, have announced their departures. Zhang, who reduced Grok's factuality error rate by up to 80%, confirmed his exit today. Zhuang, a former OpenAI contributor, left earlier this year, while Haxton, who developed Grok's voice features, confirmed his departure on May 10. The departures coincide with missed deadlines for Grok's model releases. Despite Elon Musk's April announcement that Grok 4.4 and 4.5 would be released in early and late May, respectively, the 1T parameter Grok 4.4 has yet to be unveiled. This talent exodus, affecting both co-founders and core model teams, raises concerns about xAI's ability to deliver on its ambitious model development timeline.