With no Scriptural authority to exist, mission boards usually contain some experienced missionaries who can spot potential failures before they get through. But since most missionaries fail, mission boards are not eliminating enough candidates.
One fellow here in Mexico has been driving a van for years, without pay, for an orphanage. He has accomplished far more than most missionaries in the area, but no mission board would accept a candidate whose only service is to drive a van. I'm a Baptist who drives a van on Sunday for a Pentecostal church, and on a typical week-end I'll bring more Mexicans to church than most missionaries ever will. But no mission board would ever accept me.
A retired doctor and nurse have started a successful Christian orphanage here, but with no experience in the ministry, they are here on their own. And my pastor came here after being rejected by a mission board, took a church running a dozen, and five years later is running over 100.
Mission boards must be doing something wrong, but what is it?