There's no reason Kim shouldn't be the #5 starter when he comes back. He was only throwing 86 cuz it's a rehab
assignment... he's not at 100% yet.
Kim is the much better pitcher... as a starter for the Diamondbacks and Red Sox last year he had 12 starts (including 7 quality starts) and posted a 3.38 ERA. Arroyo on the other hand, with 31 starts (and LESS than 7 quality starts
) Has an ERA well over 5.
Kim is younger, more experienced, and more talented. Kim will be the sox #5 starter