The authorative work on Oxford and his contemporaries at the court of Elizabeth is The Elizabethan Courtier Poets by Professor Steven May, one of the very few people qualified to call himself an expert in the field.
His verdict underlines the difference between those who write about Oxford searching for the truth with respect for the evidence, and those who write about Oxford without the slightest respect for the evidence in order to make a name for themselves.
If you look hard at anything written by Oxford, you can see that no germ of the writer we know as Shakespeare is in his work. As Professor May says;
"As I worked on my edition of the Earl of Oxford's poetry during the 1970s, I hoped, as I still do, that I might find some connection between De Vere's work and the writings, any writing, of William Shakespeare. Unfortunately, I discovered instead a gulf between the two poets' styles that rules out any direct ties between their output. I looked further into De Vere's life as I prepared my book, The Elizabethan Courtier Poets. The facts of his biography and career at court made any connection with Shakespeare or his writings even less likely. I regret these enforced conclusions, however, because no one has more to gain than I from discovery of persuasive evidence linking Shakespeare's works with Oxford. That discovery would catapult me from my obscure role as a professor of English at Georgetown College to the exalted status of a pioneering editor of the poems of "Shakespeare.
In 1920 J.T. Looney launched the Oxfordian hypothesis with publication of "Shakespeare" Identified in Edward de Vere the Seventeenth Earl of Oxford. From the beginning, the Oxfordian case was anchored in Looney's belief that Oxford's verse resembles Shakespeare's so closely as to reveal a common authorship. In Chapter Eight of "Shakespeare" Identified, he prefaced his comparative analysis of their poems with the admission that "our case will either stand or fall" as readers are convinced that De Vere's poetry does in fact "contain the natural seed and clear promise" of Shakespeare's verse ..."
If you are willing to consider the writing, the task of convincing people of any connection between Shakespeare's verse and Oxford's is an impossible one, yet the whole Oxfordian edifice stands upon this foundation.
As Looney himself admits.