I haven't been on this thread before; just posted a couple of comments on William's other one, "Commander/commanders of the northern flank". Happened to notice this one, so here's an observation or two on the ORIGINAL question on this thread:
The South didn't ignore the northern/western flank, so much, as it just didn't have enough manpower early in the war to effectively defend it. By definition, the Confederacy had to use troops provided by the individual member States. They were forced to use the umpty-umpth Texas Cavalry or the somethingth Mississippi Infantry, etc, trying to marshal enough forces in whatever area faced the most imminent threat.
Command and control over long distances was tenuous at best and impractical in most instances.
FWIW, one of my collateral relatives was in John Bell Hood's 4th Texas; an ancestor was a 17-year-old in the 14th Texas Infantry in the Red River Campaign.