Moving Chris Sale to the starting rotation absolutely is the right move for the White Sox. If Sale enjoys even moderate success as a starter, he'll provide a whole lot more value to the team than if he remained a dominant reliever.
But Sale still has to prove he can pitch as a starter. He doesn't have any professional experience as one, so a few things need to be monitored closely this spring to give us an early idea of whether or not he'll be successful.
Sale's slider is filthy, that much we know. He'll continue to terrorize left-handers with it, and it's not an easy pitch for righties to hit, either. But Sale leaned heavily on his slider in 2011, throwing it 36.4 percent of the time. Only one starter -- converted Texas reliever Alexi Ogando -- threw a higher rate of sliders last season.
It's possible Sale can keep throwing his slider at such a high rate, but expect him to use it with a little less frequency than he did in 2011.
He'll also have to dial his fastball back a bit velocity-wise, since he won't be able to go max-effort on every pitch as he was able to do out of the bullpen. That means he won't be able to blow hitters away as easily with his fastball, so he'll need to show good command of it in the low-to-mid 90's. There's a whole lot more room for error when you can whip a fastball in around 97 miles per hour.
Sale won't need a Mark Buehrle-level of command to succeed, but he'll have to be able to place his fastball inside and outside. There may be some bumps along the way, and perhaps Sale will allow a few home runs in spring training, but he should have a good opportunity to work out the kinks in March.
His changeup is the next key. Sale threw that pitch 11 percent of the time in 2011, using it more often early in counts -- although he would occasionally show it with two strikes.
It's not like Sale completely scrapped the pitch as a reliever, which is good. And according to Fangraphs' pitch values, it's been a very successful pitch when he's used it since coming to the majors.
Sale doesn't have to use his changeup more as a starter, but it couldn't hurt, especially against right-handed heavy lineups.
So when Sale's first spring outing rolls around, keep an eye on these four things: His fastball command, fastball velocity, slider use and changeup effectiveness. If all those factors mesh together, Sale has a chance to be an ace.