Adam Clarke on Matthew 11:9

A prophet? yea - and more than a prophet - That is, one more excellent (περισσοτερον) than a prophet; one greatly beyond all who had come before him, being the immediate forerunner of Christ, (see below), and who was especially commissioned to prepare the way of the Lord.

This was a fourth excellency: he was a prophet, a teacher, a man divinely commissioned to point out Jesus and his salvation; and more excellent than any of the old prophets, because he not only pointed out this Christ, but saw him, and had the honor of dying for that sacred truth which he steadily believed and boldly proclaimed.