John Nelson, “Can we know what Jesus really said?” (2.11.24), behindthegospels.com.
How do we know that the oral tradition was more stable than the Telephone Game?
One reason is the stability of the (once oral) traditions found in the Gospels. According to Jimmy Dunn, the Gospel traditions follow the principle of ‘variation within the same.’ This is characteristic of the preservation of oral traditions, passed on in a stable (yet uncontrolled) environment.
Another reason is the inherent memorability of some of Jesus’ sayings. Robert McIver likens the memorable form of some of Jesus’ teaching to the telling of a joke. There are typically slight variations in the way one tells a joke, but if one doesn’t remember the punchline, the joke itself is lost to memory.
The Gospel traditions were further aided in their transmission by several hallmarks of memorability, such as their their terseness [sic], vivid imagery, and aphoristic structure. While memorability and stability are not necessarily authenticity, these clues suggest that the teachings of Jesus were not completely lost in transmission.
The Amateur Exegete 