Today, almost everyone exercising church leadership is called a pastor, as if the responsiblity and authority of church leadership (bishop/elder) tracked congruently and exclusively with the gift of pastor/teacher. That is unfortunate because I think it clouds the scripture and confounds our practice. I don't see that as what was ocurring in the biblical church, nor is it what is suggested in Ephesians 4.
In that passage we are told that leadership could come from any of four (or five depending on your take on the passage) gifts or, perhaps, even a combination of those four/five gifts. All four are are the subjects of the leadership action which prepares God's people for works of service, so that the body of Christ may be built up. Properly applied, this passage means a church could be led (bishop/elder) by an apostle, or a prophet, or an evangelist, or a pastor/teacher.
That is, in fact, what happens in practice, regardless of whether or not our theology describes it that way.
Although we call them pastor if they lead a church, their true gift is going to make itself known in the execution of their duties. A church "pastored" by an evangelist is likely to stress the invitational message reaching the unbelieving. A church "pastored" by a prophet is likely to stress the revelatory message. A church "pastored" by an apostle is likely to stress getting the church planted. A church "pastored" by a pastor/teacher is likely to stress discipleship.
I think that actually explains the imbalance we often see in a church's ministry.
Our response to one-sided church emphases is sometimes to criticize, i.e. "the pastor is too focused on ______ ministry." However, I think churches need to understand the nature of church leadership as I've sketched it out here and patiently work with their leaders to get gifts expressed that their pastors do not operate in. If pastors and church folk work together, I think balance in ministry can be achieved. I do not believe that diversity in leadership gifts is meant to produce handicapped churches, as it often seems to, but instead full-bodied expressions of the manifold grace of God.