Just curious about something: I've seen a couple of my pitchers with starter ratings that I've put into the bullpen do miserably. They've done much better as starters is why I'm asking.
Is there anything to this? Should they not be used as a reliever?
Do makeup, temper and patience have anything to do with this or are these just outliers?

I've wondered the same thing honestly, although I bet part of it is you pitch more innings starting and thus have more time to even out.

Small sample size may be what you're seeing.

When it comes to pitching, ratings are ratings. The only drawback I've ever seen to using a starter in the bullpen is that if his pitch count is more than about 1/3 of his stamina, he'll take longer to recover than a reliever.

This guy is a low stamina starter with pretty decent durability (62 stam, 27 dur). Except for one season when he was in rotation, he's been a reliever with pretty decent results.

https://www.whatifsports.com/hbd/Pages/Popups/PlayerRatings.aspx?pid=9369088