The early nineteenth century was characterized by work on the OT including Isaiah that rejected or ignored the Christian tradition of interpretation of the OT, and relied instead on growing knowledge of the ANE as a clue to the meaning of all sorts of words in the OT. It was also a period in which increasingly rationalistic approaches were taken to the miraculous in the text, and the problems of seeing a unity in the whole book of Isaiah in terms of authorship was made clear.
There was a conservative response to all this by E.W. Hengstenberg, and his disciple J.A. Alexander, but only the latter wrote a commentary on Isaiah. Alexander spends his time doing apologetics, refuting the arguments of the radicals about Isaiah. He does so not with polemics but by using rational arguments of a literary, philological, or historical sort. He really doesn’t offer anything new in terms of the interpretation of the meaning of the text.He does not much interact with the church fathers, and he opposes allegorical interpretation or even Grotius’ double sense interpretation of Is. 9.6. He does allow that the servant passages refer to the messiah, and Is. 40-65 give us a preview of the glorious change the church is still awaiting. He assumes the unity of OT and NT, he does not argue for Isaiah as Christian Scripture.