Re: Volantis, he's a great test case. Freshmen, even very high end ones, often won't have the stamina to throw starter innings all year. If you have the staff to allow it (i.e., 3 capable weekend starters) you throw them on Tuesday to see if they can navigate a lineup 2-3x in a game, and then you use them in key bullpen roles on the weekend.
Starter v. Reliever considerations:
1. Pitch mix - do you have a deep enough repertoire to keep hitters from knowing what's coming the 2nd+ time through the lineup?
2. Stamina - do you have enough juice to get through the 5th? And as you tire what is the impact on your stuff. Do you throw a 2-seamer that actually picks up movement? Or do you use a 4-seamer that flattens out and ends up in the parking lot.
2.5. what is the difference between your stuff "all out" effort vs. 80%? We've seen this with multiple people in recent years... Cortez, Sdao, etc. They can come out of the pen with max effort and dominate. But as a starter, knowing they need to keep some in the tank and they falter badly. Can also go the other way where you're too amped out of the pen and can't locate at max effort, but the smooth delivery plays.
3. How able are you to adjust in-game? This is also a mental makeup issue. Can you go deep into counts, and work through the on base situations that you're more likely to see if you pitch 4+ innings.
4. How do you warm up/prepare? Less of an issue, but can you "get hot" quickly? Some guys that are career starters can't get ready quickly. They're creatures of habit and their warm up routine can be measured in hours, not minutes. It's 40% physical and 60% mental.
...and a dozen other small factors that vary player to player.
