Worship leaders, more than most other church staff roles, seem to come from within. Not in all churches, but with a higher than pastors, youth pastors, etc; many worship leaders seem to have attended their church before serving on staff.
There are probably many factors for this: Culture of the worship style, budget / salary is part-time, students are often involved, a leader is raised up from within the church over time (there may have been an outside leader for a while, but it the role was filled with an existing team member after the leader left).
I began reflecting on the benefits of having someone already connected to the church lead in worship:
1) They know the congregation. Knowing the congregation is a help because it opens doors to being held accountable, recruiting volunteers, being in the loop on scheduling / events / visions, etc.
2) They have proven track record of faithfulness. This may be in a variety of ways – worship attendance, volunteer role in the band, etc.
3) They have a history with the church and are able to help move forward from there. When you know where the church has come from, you have a different view of where it can go.
4) They have a handle on the style of worship and the way the church responds best in worship. People need to be prodded along to newer heights, but they need to be led there lovingly. One of the best ways a worship leader can aid in this process is to get into their culture, then move forward from there.
5) They’re planted. Being planted in ministry is really important for any role. No matter what church you are serving – you need to be solidly committed to and dreaming about the future with that particular ministry. When a worship leader is tied to the community / area /church, they can handle more rough waters than a transplant can.
Of course, there are downsides to a homegrown worship leader too. I also must note that an outside worship leader can definitely acquire these aspects and be effective in ministry. It always comes down to where you are called to serve. Who is the Lord leading to serve in your church?