Don't know why they're rated where they are, but looking at their stats...Having Thiero above Boswell, Oweh and Mark is insane ... Dude averaged 7 & 5 ...
Thiero is ahead on WS/40 and ORtg-DRtg. He was more efficient (by TS%) than all of those except Mark, and had way more rebounds and blocks per possession than all of them. Much lower on assists though, and slightly lower on steals. He had low usage and low minutes, so there's a big unknown on how he'd do with starter minutes/usage.