Opinions expressed by Entrepreneur contributors are their own. Key Takeaways Most CMO hires are set up to fail before day one. The root cause isn’t about talent or market conditions; it’s about early role ambiguity. Successful CMO tenures depend on explicit upfront agreement on three things: what success means, the time horizon for evaluation and what authority the CMO actually has versus the CEO. Before hiring, CEOs should write down and rank the three most important outcomes they expect from marketing in the next 18 months, along with what they’ll stop doing to give the CMO authority to execute. The data is consistent and brutal. Average CMO tenure is now 3.1 years , the shortest of any role in the C-suite. Every year, there are new articles explaining why, and every year, the number stays the same. The standard diagnosis blames marketing attribution, board impatience or changing market conditions. All of that is real. None of it is the root cause.…