Complex sentence: He speculates that only "The Merry Wives of Windsor" was Shakespeare's own work and suggests that Ben Jonson wrote most of "Hamlet", Shakespeare himself contributing only the grave-digging scene.
Split into simpler sentences: He speculates that only "The Merry Wives of Windsor" was Shakespeare's own work. He also suggests that Ben Jonson wrote most of "Hamlet", Shakespeare himself contributing only the grave-digging scene.