A) His ability to triple local church attendance in 24 months or less
B) Paul's experience pastoring a large church with multiple full time staff.
C) His impressive academic credentials and communication ability.
D) His larger than life personality and his Christian celebrity status. Paul would have been a keynote speaker at all the major conferences. He also was the author of 13 best-selling "books."
E) His ministry scars and his spiritual purple hearts.
The answer Paul gives in 2 Corinthians 11:16-12:10 is E). If we are being honest we'll admit that 2 Corinthians 11:16-12:10 is a counter cultural text to modern day evangelicalism. Many search committees judge success and ministry potential using a much different criteria than what Paul sets forth in his Corinthian epistles. I have heard of more than a few search committees of "Bible-driven" churches ask questions and eliminate potential candidates because they could not check boxes A, B, and/or C. This seems to be especially true of local churches that are larger than 500 people.
Many years ago A. W. Tozer put it this way, "It is doubtful whether God can bless a man greatly until he has wounded him deeply." Few servants of Christ suffered more for the truth and for the Lord's church than Paul.
On rare occasions you will talk with a mature lay leader like Tom Gibson from Christ Fellowship Baptist Church. Some years ago this particular elder team had the daunting task of hiring Dr. Steve Lawson's ministry successor. One of the traits this leadership board said they were looking for as they went about the pastoral search process was to find potential candidates who had been "tested by fire" (as Dr. Lawson had been previously). Rather than viewing Corinthian-esq battle wounds as a liability they viewed battle scars in the line of duty as a mark of maturity (James 1:2-4).
In his classic book on Spiritual Leadership J. Oswald Chambers noted,
When God wants to drill a man
And thrill a man
And skill a man,