Its not a silly argument anymore nor was it ever. Going from reliever to starter is a lot harder than starter to reliever and it does take a toll on your arm. Look at guys like Smoltz a few years a go and Dempster this year. They both relieved the year before but knew going into the offseason they were starters and could train as such. Smoltz did very, very well and Dempster is having a career year. Both had arm injuries the years before. Joba was best served starting the year as a starter if that is what they wanted in the first place.
Rumors have it Joba will come back as a reliever again
