Amateur Shakespearean here. I've often wondered why these statistical approaches don't look for stylistic signatures. For instance, several plays are linked by their use of doubles (in Hamlet, this scales from "too, too solid flesh," up to the running joke on the interchangeability of Rosencrantz and Guildenstern). Shakespeare also seems to be especially fond of puns on "bear" and "born" -- the "to be or not to be" monologue has three or four of these. There are also ways in which scenes repeat their designs -- 1.2 of Hamlet is similar in some ways to 3.2 of Julius Caesar, etc.