I heard on the soxprospects.com latest podcast that the Sox plan to use a 6 man rotation the first 2-3 times through the rotation to start the 2019 season.
They doubt Wright will be ready by opening day after November knee surgery. Velazquez has options, so they weren't sure he makes the opening day roster, so I guess the 6 would be: Sale, Price, Eovaldi, Porcello, ERod & Johnson.
They think the Sox are not looking to sign a RP'er to more than a year, because they have faith in the pipeline: (Poyner) Lakins, D Hernandez & Feltman
http://news.soxprospects.com/2018/12/podcast-ep-150-we-know-what-roman.html