Abetted by a wife (Marsha Stephanie Blake) who questions his manhood, Macbeth (Jonathan Cake) murders King Duncan.

Shakespeare’s Macbeth is a serial killer, right? Before he comes onstage he’s already hewed an opponent in battle “from the nave to the chops.” During the play his frenzy for gore increases, as if slaughter’s his only nourishment. He’s savage, monstrous — nay, evil aflame. So why, then, is the play a tragedy and Scotland’s public enemy number 1 a tragic hero?

The Old Globe’s production, on the outdoor festival stage, has no answer. Jonathan Cake’s high-pitched, over-e-NUN-ciating Macbeth comes off as a skittish Hamlet impersonator rather than the vile Scot “smacking of every sin that has a name.” And the production, parts staged in a World War I mental asylum, offers no tragic stature for the “dead butcher” and his “fiend-like queen.”

Macbeth knows how to kill, but he has never committed murder and fears the consequences. Killing in war has legal sanctions. But murder, especially of a king, will shoot you to hell on a lightning bolt.

Hamlet must kill the king. And, according to his father’s ghost, he must somehow remain pure. That thought sends the Dane spinning for four acts with what Norman Mailer once called “moral vertigo.” It’s as if Hamlet lives the consequences before the crime.

Assured by freaky beings that he will rule Scotland, Macbeth must also kill a king. Abetted by a wife who questions his manhood, Macbeth murders King Duncan. For the rest of the play he must slay the consequences, in his mind and in fact, as a new opponent rises when another falls. Hamlet spins inside. Macbeth must stop the world from spinning. It’s as if he tossed a stone in a pond and must chase in all directions to prevent concentric circles from multiplying.

You could say Macbeth earns tragic status in the clash between his afflicted conscience (and the majestic poetry it produces) and his blind brutality.

He craves speed, to leap from the thought to the deed and catch “the future in an instant.” So you’d assume his speech would fire daggers as well. Not Jonathan Cake’s herky-jerky Macbeth. He stops midsentence, with a lengthy pause, then proceeds, often running on to the next: “Is this a...dagger which I see?” The choice works at first. Macbeth is thinking on the spot. But he isn’t. It’s just an annoying mannerism and, with one of the most famous lines of all, just bad acting: “A tale told by an” — long, long pause, then, with scrunched face — “idjit.”

Cake talks like a sportscaster. But the Jack Buck Approach to the Bard doesn’t work at all.

Marsha Stephanie Blake is either miscast or misdirected as Lady Macbeth. Until the sleepwalking scene, where she opens up to good effect, Blake has no emotional size. She reads the spine-tingler, “Unsex me here,” as if ordering a salad.

The show opens in the antiseptic white ward of a mental asylum. Six beds half-circle the rear stage. Macbeth enters. But why the ward? Why, if he’s wounded, not some emergency triage on the battlefield? When the heavily bandaged patients prophesize his future, the scene makes a kind of sense: are they or are they not credible?

But wouldn’t Macbeth, even if over-adrenalized from hewing, consider the source?

Many of director Brian Kulick’s choices have this perplexing quality. Why, for example, do we watch Macbeth slay Duncan? (Most commentators say we shouldn’t see the deed, since it makes him too evil too soon.) And why, when Macbeth slays Duncan, does he have his back to us and merely ruffles the white pillowcase and sheets? Why such tasteful mayhem?

Some touches take hold. The hospital lights flick the fateful dagger across the rear wall, evading Macbeth’s reach. The coup de theatre staging of the banquet/Banquo’s ghost scene: follow the bouncing Banquo as the table turns without a turntable. Also in the drunken Porter’s scene, as the door knocks endlessly, he has a female partner, a nurse, just as snockered. The comic dialogue includes both. These choices show a deft hand at work.

But why interject comedic bits into more serious scenes? When the Macbeths plot regicide, the rear door opens on occasion to bright lights and the shouts and chants of a hartay-partay in mid-debauch.

Few in the cast, as Hamlet instructed the Players, “suit the action to the word.” Those that do, stand out: Timothy D. Stickney’s Banquo speaks and feels so effectively it’s almost as if he came from another show. Clifton Duncan (Macduff) and Daniel Petzold (Malcolm) combine for the production’s best scene — Act IV, scene iii. Malcom, who will sire a progeny of kings, tries to out-Macbeth Macbeth, then confesses virginal innocence. The exchanges are simple, the actions clear. It’s a history lesson well dramatized. That this scene, which directors and dramaturgs usually want to blue-pencil to pieces, would be the most effective speaks volumes about the rest of the Old — lengthy pause, lengthier pause — Globe’s production.

Macbeth, by William Shakespeare

Old Globe Theatre, Lowell Davies Festival Stage, Balboa Park

Directed by Brian Kulick; cast: Jonathan Cake, Marsha Stephanie Blake, Jerome Preston Bates, Daniel Petzold, Timothy D. Stickney, Kevin Hafso-Koppman, Clifton Duncan, John Lavelle, Mark Pinter, Makha Mthembu, Amy Blackman, Suzelle Palacios; scenic design, Arnulfo Maldonado, costumes, Oana Botez, lighting, Jason Lyons, sound, Sten Severson and David Thomas, fight director George Ye

Playing through July 24; Tuesday through Sunday at 8 p.m. theoldglobe.org