The Union general ratings are ridiculous

[dude]

Yup that was part of it... there were actually a number of minor things Halleck tried to get Grant on. He claimed Grant’s men had looted captured supplies from Fort Donelson. The Nashville incident was a bogus one on Hallecks part...

"Halleck complained to the War Department that Grant had left his command without authority when he visited Nashville. He did not mention that Grant had specifically informed him in advance: 'I will go to Nashville... should there be no orders to prevent it.’ Halleck was trying to build a case for Gran’s removal, and anything would do.” Ulysses S. Grant – Soldier & President (Geoffrey Perret)

[General Quarters]

With regard to McClernand: during the Vicksburg campaign, Grant had the problem that McClernand had seniority in rank over Sherman and the other commanders, so Grant always had to post Sherman at the crucial place, so he could be in charge, and put McClernand somewhere else. It made life complicated.