Melody Moore as Lady Macbeth and Eric Owens as Macbeth in The Glimmerglass Festival's 2015 production of “Macbeth.” (Karli Cadel/The Glimmerglass Festival)

Stage direction is the most controversial element of today’s opera world. And stage direction divided opinions about the just-concluded 40th season of the Glimmerglass Festival — fittingly, since the festival is run by a stage director, Francesca Zambello.

Not everybody wants the kind of updating Anne Bogart offered in her 1930s version of Verdi’s “Macbeth.” Not everybody wants the biting sarcasm Zambello brought to Bernstein’s “Candide,” the token musical of the season. Both productions, though, offered a lot to like — and, most important, inspired some strong vocal performances, which is the point of the exercise. This was one of the strongest Glimmerglass seasons I’ve seen.

At both Glimmerglass and the Washington National Opera, where she is artistic director, Zambello has aspired to build a “home team” of young singers, giving opportunities to current and former members of the apprentice program — a goal shared by many U.S. companies today. I have some mild general reservations about the ubiquity of the apprentice system, with its odd combination of mind-numbing hard work and artistic coddling. But there’s no denying the appeal of watching an artist like Soloman Howard, a past member of WNO’s Domingo-Cafritz Young Artist Program, grow into his voice and shine in a main role such as Banquo in “Macbeth” — alongside other former WNO young artists who sang leads here this summer (Jacqueline Echols as Pamina in “The Magic Flute,” Andrew Stenson as Candide).

There were other Washington connections. Ryan Brown, the founder and artistic director of Opera Lafayette, made his Glimmerglass debut conducting “Cato in Utica,” while John Holiday, who sang Handel’s Caesar so well at Wolf Trap last summer, was excellent as Vivaldi’s version of the same character: a voice both sweet and ardent, and an effective stage presence.

The stage direction wasn’t controversial in “Cato”: Tazewell Thompson’s thoughtful production was beautifully framed by the dusky red Roman ruins of John Conklin’s set. And the pacing of baroque opera was picked up here, due to dramatic compression: Act I of “Cato” is lost, and this production opted simply to present Acts II and III, after filling in the plot outlines with brief thought bubbles projected above the characters’ heads during the orchestral prelude. The singers, notably Allegra De Vita as Fulvio, Sarah Mesko as Emilia and Megan Samarin as Marzia, also did their best to offset stasis.

Megan Samarin as Marzia in The Glimmerglass Festival's 2015 production of Vivaldi's “Cato in Utica.” (Karli Cadel/The Glimmerglass Festival)

The production also finished particularly strongly. When “Cato” premiered in 1737, its tragic ending went over so badly that the creators tacked on a happy one for subsequent performances. Glimmerglass returned to the spirit of the original Metastasio libretto and offered a silent tableau of Cato’s suicide, and the characters’ reaction to it, enacted during a beautiful orchestral postlude: not necessarily true to the period, but eloquent nonetheless. (Opera Lafayette will perform a semi-staged version of the work, with some of the same singers, at the Kennedy Center’s Terrace Theater in November.)

For those who still frown on Glimmerglass’s embrace of American musicals, “Candide” is a fine compromise; with its shifting, syncopated score and vocal riches, it’s not out of place on an opera stage. Indeed, the only questionable casting move was using the musical actor David Garrison, instead of an opera singer, as Voltaire/Pangloss; he was dramatically sound, but vocally weak, which removed the zing from a couple of the big songs. (The same could be said of Marietta Simpson’s otherwise delightful, character-ful Old Lady.)

But “Candide” is in any case a problem child; it was written and rewritten and still doesn’t entirely work, and no staging can quite paper over its dramatic flaws (such as a second half that feels, until the end, largely extraneous). Zambello kept sight of the biting darkness under the zany humor, never more than in the brilliant staging of Cunegonde’s aria “Glitter and Be Gay.” This piece has become a comic staple of the coloratura repertoire, but Kathryn Lewek (as Cunegonde) and Zambello stripped it of its coy cuteness and found the rage and pain of a woman forced to be a mistress to two powerful men; Lewek snarled out flawless coloratura with so much power that even Jennifer Moeller’s somewhat awkward corset-costume made sense as an imprisoning symbol of pseudo-sexuality. The highlights of Zambello’s directing career, in my experience, have been the moments when she brings new and lasting insight to a familiar character; this scene was one, and it won me over to her concept.

When leaders back an artist they believe in, it’s a good thing, unless we don’t like the artist, in which case we label it stubborn and stupid. Zambello has remained loyal to the visionary Anne Bogart, who created a compelling “Carmen” here and a not-very-good “Norma” in Washington, and, now, a somewhat subdued “Macbeth.” One of this opera’s challenges to a director is the chorus of female witches, “Double, double toil and trouble” and all. Bogart turned them into the domestic staff of the Macbeths’ home, in and out of uniform, their watchful eyes on every aspect of the couple’s lives — an idea that certainly brought spice to the concept of a threatening and ubiquitous female chorus, even if it didn’t always work. The updating arguably got a little out of control with the “Patria oppressa” chorus, because bringing a crowd of 1930s-era refugees inevitably bears Holocaust evocations that threatened to overwhelm the story.

However, the singing was so good it didn’t really matter. Eric Owens, a staple at both Glimmerglass and WNO, seems to be intent on staking out baritone as well as bass-baritone territory; his strong, firm, intense Macbeth was some of the best singing I’ve heard from him in a while. Melody Moore took admirable risks with a voice I might have thought a little light for the part, expertly navigating the role with small piercing top notes, deep low ones and solid dramatic comprehension. Howard excelled as Banquo, and Michael Brandenburg, a current Young Artist, brought down the house with a nervous, edgy, taut version of Macduff’s anguished aria.

And Joseph Colaneri, in the pit, showed a fine grasp of Verdi. The veteran Colaneri has been Glimmerglass’s music director since 2013 and is a savvy choice for this particular festival. He excels at working with young singers and is good at the standard repertory (though he couldn’t entirely lighten up the orchestra’s heavy winds, and “Candide” was a little sloppy). When music and staging are working in tandem, opera is generally in pretty good shape, and Glimmerglass can pride itself on the close of a happy 40th anniversary.