Most leadership teams are formed by chance.
You have an open role, you recruit a domain expert to fill the position, and you make a hire. Rinse and repeat for every opening—each hiring decision is made independent of the last.
Sometimes it works out well and the whole—your collective team—is greater than the sum of its individual parts. But often, it’s not.

All too often you end up like my friend, who shared some of their workplace challenges with me the other day.
As we discussed the issues and root causes, we had an unexpected realization—their leadership team is comprised entirely of folks who have never served in senior leadership roles before. Perhaps not surprisingly, this was contributing to many of the problems they were experiencing.
Wanting to develop new leaders is laudable. Putting your company entirely in the hands of new leaders is not.
Pieces of a puzzle
Building a team is like completing a puzzle, one where you’re trying to find the perfect piece that not only fits the spot (domain expertise) but also completes the picture (fills out the team).
Have a lot of newer leaders? You may want someone more experienced to help mentor and develop the team.
Is there a lot of tenure on the team? Perhaps someone with an outside perspective would be a good addition.
Under the gun to deliver immediately? An internal hire may be able to ramp and make an impact more quickly than bringing someone in from the outside.

A framework for building teams
When I was a CIO, I was frequently hired to transform an institution’s IT environment and team. The leadership team I put in place was critical to fulfilling this mandate.
Diversity was (and is) important to me in how I built those teams. In addition to looking for usual aspects of diversity like gender and race, I thought broadly about the diversity of my leadership team and looked for diversity of experience, perspective, and individual strengths, among other things.
This diversity was key to building a leadership team that could drive the change we needed. As I built out my teams, I looked for three things:
Untapped potential within IT. Trust is essential for driving change. There may already be change-makers within your organization who are well-respected by their peers and have leadership potential. It’s important to elevate these folks—it demonstrates your belief in and respect for the current team, which is important, and their support for your vision will help bring others along more quickly.
Talent outside of IT, but inside the institution. If you’re brought into an organization to drive change, it’s likely because your stakeholders think something is broken. Even if they don’t, driving organizational change will require stakeholder buy-in. In either case, having folks on your leadership team who come from other parts of the organization, can represent their perspective, and can build bridges between your team and your stakeholders adds tremendous value to the team. Find talented and trusted folks who are frustrated with your team and want to help drive change from within it.
Skills you needed to bring in from the outside. You may need skills that don’t exist in your team or organization today to drive true transformation. Newer technical skills, more innovative ways of working, and disciplined professional practices (e.g., project management) may be areas where your current team just doesn’t have enough expertise. While any of these can be learned, identify strategic levers for change and then make expert-level, external hires to drive the type and pace of change you need.
I used this framework across multiple organizations to build teams that could lead change in a university IT organization—and it worked. YMMV.

Your own organizational needs may be different, and your model should reflect that.
Whatever your goal is, taking a broader view—one that recognizes the capabilities you need in a role and those that you need on the broader team—will help you build a dream team that can help you achieve it.
Bonus read: As you are putting your leadership team together, remember …