I see (belatedly) a body of revision continues to be built up re the Vicksburg campaign.
A recent Usenet post marks out a line of thought represented by Ed Bearss, Terence Winschel, and now Timothy Smith that "believes that Grant put McClernand across the Mississippi River first and then used McClernand to screen ... because he knew that McClernand was his best fighter." [I have quoted the poster, not the authors.]
Grant scholar Brooks Simpson responds in the same thread, that on the contrary, "He wanted to keep an eye on McClernand," and "Grant liked McClernand's subordinates." He concludes offhandedly, "I think the dump on McPherson/praise McClernand stuff goes too far in presumably correcting a McClernand as idiot/McPherson as great fellow argument."