Have You Seen This, James Tabor?

On Parchment and Pen, C. Michael Patton has posted an interesting summary of the traditions surrounding the various deaths of the Twelve. Interestingly, he apparently equates James the Less (James the son of Alphaeus) with James the brother of Jesus, as he associates the martyrological traditions of the latter with the former:

(8) The Apostle James the Lesser

James was appointed to be the head of the Jerusalem church for many years after Christ’s death. In this, he undoubtedly came in contact with many hostile Jews (the same ones who killed Christ and stated “His [Christ's] blood be on us and our children” (Matt. 27:25). In order to make James deny Christ’s resurrection, these men positioned him at the top of the Temple for all to see and hear. James, unwilling to deny what he knew to be true, was cast down from the Temple and finally beaten to death with a fuller’s club to the head.

Date of Martyrdom: 63 A.D.

Probability rating: B that he was cast down from the temple, D that he was being beaten to death with fuller’s club after the fall

Although Michael does not list the sources of these traditions, this cause of death is given, in slightly varying forms, by Clement of Alexandria and Hegesippus (via Eusebius of Caesarea). However, another account reported by Josephus (and also incorporated by Eusebius) gives the cause of death as stoning. Many scholars hold that this latter narrative is more historically probable. In general, I'm curious as to the nature of his ratings... what causes him to preference one tradition over another? Perhaps questions of dating?