What is the burden of failing to provide adequate counsel on appeal?

counsel [citation], and there is a "strong presumption that counsel's conduct falls within the wide range of reasonable professional assistance." [Citation.] Defendant's burden is difficult to carry on direct appeal, as we have observed: "'Reviewing courts will reverse convictions [on direct appeal] on the ground of inadequate counsel only if the record on appeal affirmatively discloses that counsel had no rational tactical purpose for [his or her] act or omission.'" [Citation.]' [Citation.]" (People v. Vines (2011) 51 Cal.4th 830, 875-876.)

C. Deficiency