Venture Capital is generally thought to be a key link in the complex chain of financing for young innovative firms. By helping them at critical stages of innovation development, it would help an economy to leverage its public research and sustain its growth. However, recent research reveals that the performance of VC funds, both internal (profitability) and external (growth), does not reach the expectations. In this paper, we aim to show that paradoxically, the theoretical model of VC conveyed by the literature does not take the management of innovation into account, and makes unrealistic assumptions on the composition of project portfolios. Conversely, based on interviews with some VC funds managers, we show that actual funds can invent alternative management models, for example based on the structuration of ecosystems for the start-ups, the development of "external valuation" mechanisms, or the creation of synergies between financed projects.