Authenticity
The New Oxford Annotated Bible prologue is correct in stating the Pastoral Epistles (1 Timothy, 2 Timothy and Titus are psuedoepigraphical, not written by Paul.
Bart D. Ehrman, in Forged, page 98, cites the British scholar A. N. Harrison who wrote an important study of the pastoral letters in 1921, giving numerous statistics about word usage. Of the 848 different words used in the pastoral letters, 306 - more than one third - do not occur in any of the other Pauline letters of the New Testament. And two thirds of these 306 words were used by Christian authors living in the second century. Paul not only did not use these words, but it seems he would not have known the meaning of some words that came into use in the second century. Moreover, some ideas and concepts in the pastoral letters stand at odds with what you find in the letters that Paul wrote.
Authorship
Most modern New Testament scholars dismiss the tradition of Paul as the author of the pastoral epistles, to the point that many writers, such as in the New Oxford Annotated Bible no longer feel obliged to give specific reasons for this view. Burton L. Mack says in Who Wrote the New Testament, page 206, the language, style and thought expressed in the pastoral epistles are thoroughly un-Pauline. Although the New American Bible emphasises any doubts about non-Pauline authorship, it still says says in the prologue to 1 Timothy:
Most scholars are convinced that Paul could not have been responsible for the vocabulary and style, the concept of church organization, or the theological expressions found in these letters.
Having ruled out Paul as the likely author of these epistles, we must try to learn what we can of the real author. Because the author wished readers to believe that the three epistles were written by Paul himself, some decades earlier, he was careful to leave us no clue as to his identity.
All we can really infer is that the author wrote during the first half of the second century and probably lived in the Greek-speaking eastern Mediterranean region. The first assumption is based on the references to second-century concepts such as 'overseers', or bishops, and on the analysis by Harrison. Francis A. Sullivan SJ says in From Apostles to Bishops, page 15, that the consensus of scholars, including Catholic ones, is that Rome did not have bishops until around the middle of the second century, so a Roman Christian would have been less likely to have written as if the appointment of bishops was an established fact. The epistle addressees and locations are convenient fictions, so they tell us no more about where our author lived. We can never know the name or any personal details about the author of these epistles.