The MO TMD units were composed of better human material than the AR units, since the AR units were mainly draftees or those that volunteered under threat of the draft, whereas the MO units were volunteers. Hence their better performance.
The colonels of Parsons' division were a mixed bag. Of the brigade commanders, Mitchell was a college student when the war started, while Simon P. Burns was a young farmer who'd had US army enlistee experience. The MO TMD cavalry had better leaders, IMO. The best MO officer material fought in the Cis-MS. For example, the Missouri West Pointers like Bowen, Lucius Rich, and Little went with Price to the Cis-Mississippi and never returned.