I found it odd that Mcpherson would argue such a position until I remembered that to suggest that the South could have won, serves to make JM's beloved North and Lincoln more admirable and to make the CSA look worse, much the way a pro-team's coach talks up the opposition so that when they are beaten, the victory is more "glorious".
The only way the CSA could have won the war was if Lincoln died or the British intervened.
BTW: I check my local used-book stores for many titles - a great source of low-priced reads for your library.