To my surprise, they cite the excellent study of Hasmonean and Roman paleo-Hebrew scripts by Mark McLean. McLean traces the typology of this archaizing script and is able to date by centuries and sometimes by half centuries paleo-Hebrew inscriptions, coin legends and manuscripts of the Hellenistic and Roman periods—including the paleo-Hebrew manuscripts from Qumran. Apparently, Rogerson and Davies did not learn from McLean’s study the characters of paleo-Hebrew and its evolution—assuming that they read it. They do not cite the paleographical literature on the development of the eighth- to sixth-century Old Hebrew scripts, and obviously have not been deterred by it.
The list of significant features differentiating Old Hebrew from paleo-Hebrew can be extended to most, if not all, letters of the alphabet. To identify them requires an eye and memory for form, gifts that make the paleographer. Without such gifts, a scholar is in the same straits as the tone-deaf musician who wishes to conduct an orchestra.