Daniel Hays argues that Goliath was "only 6 feet 9 inches tall and not 9 feet 9 inches." He concludes,
Thus, Goliath was probably about the size of an NFL lineman like Flozell Adams of the Dallas Cowboys (or perhaps I should use Michael Strahan of the Giants as my illustration?). ("The Height of Goliath: A Response to Clyde Billington," p. 516)
In the same edition, Clyde Billington responds to Hays' arguments. He rejects Hays' contention that Goliath was this height because he thinks all of the best manuscripts of 1 Samuel 17:4-7 point to the traditional reading of his height being 6 cubits (around 8 feet tall). He concludes,
Hays argues that Goliath was a very large man at 6 feet 9 inches, but not a real giant. However, there are good biblical, archeological, and historical reasons for rejecting these assumptions. . . . Goliath was about 8 feet tall. ("Goliath and the Exodus Giants: How Tall Were They?" p. 489-90)
An Alternate Theory:
After careful research, I've determined that Goliath was actually 13 inches tall, and incidentally available for $24.99.
Though, I'm still not convinced that any of these findings enables the reader to understand 1 Sam 17 better.