I agree except I wouldn't consider Petan a lock. It depends on vacancies and there are a lot of possible configurations.
We can see 3 clear vacancies in the top 9 right now, Buff, Kane and Frolik need to be replaced. We also have a number of potential candidates to fill those vacancies. Burmi, Frolik, Petan, Ehlers and whoever we get back for Kane not to mention any possible FAs. That looks like pretty good competition for those spots.
If Frolik goes (probable), Burmi comes back and 1 spot is filled by the Kane trade (both also probable) that leaves Ehlers and Petan competing for the remaining spot. I don't think we can predict the outcome of that very well yet. If it is close I would lean toward keeping Ehlers and sending Petan to the Rock because Petan would then be freely available for call-up. He could go up and down several times through the year if necessary and would likely spend most of the year with the Jets. There are always injuries. In hindsight we should have kept Petan this year instead of either Hali or Gali. They could have taken turns going up and down and we would have had plenty of use for Petan, especially right now.