I am somewhat inclined to agree, but in fairness to Hardee, he had three really good days as a corps commander in the war - Stones River (the December 31 assault in particular), Averasboro (a classic study of defense in depth), and saving Johnston's line of retreat from Mower at Bentonville.
Yet Albert Castel stated in Decisions in the West that by July of 1864, Hardee was, with perhaps the exception of Longstreet, the best corps commander in the Confederacy. I think the historical record does not bear this out. His performance on the whole at Shiloh was good but problematic. His first major action as a commander of more than a company makes me inclined to forgive how his command splintered, given the rough terrain and fierce resistance he encountered. He did very well helping to organize a defense on the right during April 8 counterattack, yet his baffingly refusal to forward Forrest's intelligence about Buell's arrival the night previous to Beauregard is one of the worst decisions made in the battle and helped to bamboozle Beauregard about where the Army of the Ohio actually was.
His performance at Perryville was okay, but his poison pen campaign with Polk that began during that campaign was responsible for the toxicity within the Army of Tennessee. However, Hardee seemly disliked the responsibility of overall command yet was critical of anyone who took on the burden themselves. He would be critical of Bragg, Joseph Johnston, and Hood, yet refused command of the army when it was offered after Bragg's resignation. At Stones River, as noted above, he did very well. His assault was tactically articulate and managed as well as it could be. This could not be said for Polk's corps. Again at Tullahoma, Hardee would seemingly withold vital intelligence about enemy movements from his commander, including the notice that the gaps assigned to his corps front were being forced and that Bragg's line of communications were in danger. Without this knowledge, Bragg was actually planning an offensive with Polk's corps that only Polk's obstinate refusal prevented a disaster.
The biggest marks on Hardee's record are at Atlanta. Peachtree Creek, where he threw a hissy fit about Hood being promoted over him (and it really shows), disobeying orders and refusing to verify them, refusing to ensure that most of his divisions were commited (including not checking on Bate's lost division on the right) meant that Hardee squandered a pretty good opportunity to gobble up Newton's isolated divison of Howard's Fourth Corps. His attack gained ground at Bald Hill, but it was a terrible policed night march and an assault that he potentially launched to early (attacking the Federal left instead of its' rear). Yet for all the criticisms of Hardee's flank march at Bald Hill, it was the most successful of any of Hood's sorties during Atlanta. Jonesboro speaks to itself. Hardee commanding the field could not stop S.D. Lee from attacking early or keep Cleburne's corps from coming apart at the seams during its' assault, though to his credit he extracted his isolated corps from a pretty precarious position the next day.