I think it comes down to what the chief officers of the Department thought their priorities should be. Taylor makes the central issue recovering as much of the population and infrastructure of Louisiana as possible. I don't see a way in the world he could have retaken New Orleans, but I do think they had a shot a interdicting the traffic on the Mississippi, removing the construction and repair facilities at Algiers from Union control and regaining effective operation of the Algiers-Brashear RR. This would have put further pressure on the blockaders along the Western Louisiana Coast. Artillery fire from the West Bank might have made the wharves and docks at New Orleans untenable for the Union Navy. Union troops in New Orleans don't seem to have been numerous for most of the war and they could probably have been resupplied on a line to Ship Island and into Lake Ponchartrain and the canals. For the Union, New Orleans was a major trans-shipment and command and control center. Take away the ability to use the docks and that section of the river and the Command and Control function greatly suffers. I think Smith had a job kind of like Eisenhower's in WWII. He was nominally the head man, but had tremendous pressures politically from state governments in exile (Missouri, Arkansas, Louisiana) and Texas which contributed greatly outside their state, but refused to strip themselves to the point of vulnerability or collapse. If Smith hadn't allowed operations to the north, it might have been difficult to keep his Missouri and Arkansas units from deserting en masse. They could very easily see a concentration on operations to the East as being abandoned. Davis recognized that Smith had a unique and difficult command and told him so. Just trying to finanace the Trans-Mississippi was a nightmare. Magruder strongly believed that Texas was the key theater. We sometimes forget that at one point, a serious attempt was being made to set up a mass crossing of about 10,000 to 12,000 troops from the Trans-Mississippi to the East. It was pretty much a crap-shoot and was abandoned when Union forces moved into key positions that would have caused a massacre. Probably the worst thing that can be said of Smith is that he was a "down-side player", he played to not lose. Taylor in contrast, played to win. He didn't win all the time, but he kept the other fella worried. The limits to Smith's strategy showed up when he moved Magruder to Arkansas. If anyone could salvage something with smoke an mirrors, it was Magruder. But his reports give the impression that he felt Arkansas was cleaned out and that without the logistics to supply Confederate troops in the area, they were better off pulled back south. Smith's great mistake was probably allowing Stirling Price's raid. One observer of the time commented "...he lost 12,000 veterans and brought back 10,000 unarmed recruits." If Smith had committed to back Taylor, it is doubtful Price's raid would ever have been made.