Whether a criminal-defense attorney's deficient performance under Strickland v. Washington affects the trial's outcome or renders the trial fundamentally unfair

QUESTION PRESENTED In considering whether a_ criminal-defense attorney’s deficient performance was prejudicial under Strickland v. Washington, 466 U.S. 668 (1984), is all that matters whether the deficient performance affected the trial’s outcome? Or does it matter if it rendered the trial fundamentally unfair?