For sure Miles gets a shot at the rotation, I don't think for a second they claimed him with plan A being a leverage reliever long-term, even though he certainly could be right now.
I also agree they need to add a legit arm. Spaghetti is certainly not ready and yes he still has options.
However, I think if they want Miles to start, he will at least be starting the year in Buffalo to build up innings and get back into the starter's regimen. Cease, Trey, Ponce and Yesavage (barring injuries of course) are stapled 1-4. Signing or trading for another top starter basically means the Spencers are in Buffalo.
This is where a work stoppage would really suck for them since they wouldn't even be able to play for Buffalo since they're on the 40 man roster and 40 man roster guys can't play in the minors in a lockout.