I hope they add two starters to the team. At least one of whom has a high probability of being a top half of the rotation type and the other at least a solid ML starter. In reality, #2 or #4 starter lose meaning once the season gets going. They need five starters that can give them innings and a decent chance to win most nights. Something like
Nola
Added Starter
Arrieta
Added Starter
Eflin
Then they will need another set of starters who likely will be called on during the season to fill in for injuries or lack of expected performance.
Velasquez and Pivetta may well be used in the pen but could return to starting if needed. Both also have an option left, which can be important in keeping pitching depth.
There are also several starters that project to be at AAA (Irvin, De Los Santos, Romero, Eickhoff (will still have an option next season), Medina, and others) that could also end up getting ML starts if we have multiple injuries or failures.
Frankly, I don't see Smyly or Vargas being retained IF they can add those two new starters that I want to see added. At least one of them should be left handed. Of course, the Phillies might retain Vargas or resign Smyly, but I am hoping for better.