(L to R): Vivica Genaux, Jessica Pratt and Maestro Antony Walker in the Washington Concert Opera's performance of Rossini's "Semiramide." (Don Lassell)

Concert opera companies often end up specializing in a form of opera akin to an athletic event: The focus is turned from the drama onto the physical feat of producing the sound. The Washington Concert Opera is a fine purveyor of this manifestation of the genre, often focusing on bel canto opera, which is not much done by major opera companies (too long, too esoteric) but which, when you get good singers and an involved audience, can move the crowd-pleasing needle high up into the green.

Sunday’s offering at Lisner Auditorium was “Semiramide,” Rossini’s last Italian opera, cut into submission at a relatively modest three-plus hours, and offered a sense of the sporting event without, alas, a full measure of visceral thrill. But given the relative restraint of what was happening onstage, the proceedings were strikingly amiable. It’s nice to have a chance to hear rare Rossini, even if the orchestra is evoking what were probably the more ragtag standards of a small 19th-century Italian opera company and the singers are generally no more than pretty good.

I am perhaps lax in not worrying too much about the story. The important thing is that it sets up a framework on which to hang emotions of love and anguish and rage and betrayal: The queen Semiramis (to use her English name) loves a young man, Arsace, who turns out to be her long-lost son by the husband she poisoned. For opera fans, the work is best known for its overture, the aria “Bel raggio lusinghier,” and the duet between Semiramide and Arsace that was something of a showpiece during the bel canto revival of the mid-20th century.

On paper, the casting looked strong. Vivica Genaux (as Arsace) is an acclaimed Handelian and a WCO favorite. Unfortunately, the middle of her voice sounded foggy and weak on Sunday, although the lowest notes were full and the upper ones clean and shining; sometimes, when a singer develops his or her vocal extremes and makes the voice a little heavier, the intersection between them can suffer. Genaux is never less than a committed performer, but she wasn’t her full shining best Sunday. As for the soprano Jessica Pratt, making her WCO debut in the title role, she had beautiful colorful top notes, but overall, a rather slender instrument with not much weight to the lower notes.

A highlight was Taylor Stayton, whose bright, firm tenor rang out in the one big aria of Idreno. In the bad-guy role of Assur, Wayne Tigges offered a pushed, nasal, rather unpleasant sound. Evan Hughes (Oroe) was green but honorable, and Wei Wu, a member of WNO’s Domingo-Cafritz program, made a brief stentorian showing as the ghost of Semiramide’s husband.

Antony Walker, WCO’s buoyant artistic director and conductor, was, as always, crisp of gesture and light on his toes. But he couldn’t entirely inspire the orchestra to play cleanly. Still, the whole thing had the right shape, and if it was a flawed evening, it wasn’t a dreadful one.

The Washington Concert Opera will present Donizetti’s “La favorite” on March 4.