Many incumbents have the ambition to become ecosystem leaders when transitioning to platform business models. While most prior research has studied established consumer markets, our study extends the empirical knowledge on ecosystem dynamics with a focus on platform around industrial data. In a longitudinal study, we investigate factors influencing this transition and study in particular how industrial incumbents balance value creation and capture during ecosystem emergence. In this stage, managing openness is a key strategic decision. While openness is required for value creation, the complexity and physicality of the industrial setting hampers value capture. We identify control points to manage the tension between value creation & capture and derive different transition journeys. Lastly, we propose that in industrial markets, multiple platforms can co-exist in the same ecosystem, complementing the established "winner-takes-all" paradigm. Our research identifies situations where incumbents intentionally forfeit a leadership position in favor of joining an alliance-driven ecosystem.