I think it just comes down to money really. He’s upset he got less money in arbitration, and since he’s a free agent next year, he’s hoping to get a big contract maybe something like 3/45 as a starter. He probably feels like if he pitches in long relief for majority of the year then he won’t get that big contract he wants. And he might be right.
However, his numbers could very well look worse as a full-time starter as opposed to a long relief role. But that’s just the confidence of an athlete clouding his judgment.
And at the end of the day, he shouldn’t be airing his grievances to the media.