Even at the highest levels, you cannot overlook the fundamentals of team building and human resources. That's the big takeaway from the news that Yahoo CEO Marissa Mayer has fired COO Henrique De Castro after 15 months on the job. Specifically, two things come to mind:

1. The best top teams know how to have productive conflicts--without taking things personally. There are indications that De Castro and Mayer did not get along. Kara Swisher of Re/Code reports that he "was a polarizing figure at Google, where Mayer had hired him from [and] quickly became the same polarizing figure at Yahoo...he and Mayer had developed a tense relationship that many in meetings with the pair found it hard not to notice." 

Conflict among team members, in and of itself, is not the enemy. The enemy is when conflicts become personal. One of the signs of a healthy organization is when members of the top team can openly disagree with each other without their relationships becoming tense.

2. CEOs and COOs must complement each other. Harvard Business School professor Rosabeth Moss Kanter sorts complementary roles into three categories:

    1. Alignment
    2. Differentiation
    3. Succession

For example, years ago, when erstwhile Verizon Communications CEO Ivan Seidenberg appointed Lowell McAdam, then the head of Verizon Wireless, as his COO and successor, "This amplified the company's message about the importance of wireless technologies," she writes. Seidenberg's COO choice was in alignment with the company's mission. Today, McAdam is the CEO.

Differentiation has to do with complementary skill sets. Think of how the skills of Facebook COO Sheryl Sandberg--management savvy and government-relations experience--complement those of founder and CEO Mark Zuckerberg. As for succession, "The smooth handoff at Xerox from former CEO Anne Mulcahy to current CEO Ursula Burns is often lauded as a model," writes Moss Kanter. "Mulcahy's turnaround of [Xerox] included [a focus on] leadership development and [she] elevated COO Burns… to partner and successor-in-waiting."

How Mayer and De Castro complemented each other, we may never find out.