...Also ar Cassville from memory, Johnston picked out the position and thought it was a good one but Polk and Hood convinced him the position was not tenable, hence the withdrawal...
...The field was not picked out for it's defensive features. That only became and issue after Hood failed to keep up the offensive nature of the plan and turned it into another defense. That is why they confederates were on such bad ground day 2: It wasn't meant to be a defensive operation there.
On this matter, after Hood failed to press the attack and the chance to strike the Army of the Ohio isolated was lost, Johnston withdrew the Army of Tennessee South East of Cassville to a ridge which his engineers had identified as a strong defensive position. Johnston later referred to this position as
"the best I saw occupied during the war", and a staff officer in Stewart's division agreed, calling it
"the strongest position I ever saw..." though these were, pehaps views distorted by hindsights post-war.
Regardless, Johnston was resolved to stand and fight on that position, however Hood and Polk were not happy with it and felt they would be exposing their men to the artillery of the Federal for which they had no answer. They combined forces in the night to convinced Johnston that the position could not be held, and held their ground despite Johnston's objections to their views and attempts to convince them otherwise during a two hour long debate.
According to Samuel French, who was present, Johnston was determined to fight at this position but was worn down by Hood's obstinate insistance that the position could not held and Polk's support of Hood, and Johnston felt he could not defend the positon with two of his Corps Commander so vehemently opposed to doing so for fear that their lack of confidence would communicate down to their troops and become a self-fulfilling prophecy of doom.
Hardee felt the position strong enough to hold and protested the decision to withdraw but it was, at that point, no use and the decision to evacuate the line was upheld, thus ensuring Cassville both cemented Johnston's reputation for being....an unfortunate general and ensuring it's place as probably his biggest lost opportunity as an Army Commander.
As an asside, Napoleon was credited as having once said
"I rather have lucky generals than good ones", and whether you think Joe Johnston a good general or not there can be no doubt that he was an unlucky one.