Now in its 25th year, Nashville Opera Association has attained legitimate regional respectability, having made great strides with quality productions, progressive audience development and an annual budget that now exceeds $2 million. With the time ripe for the mounting of the company’s first-ever original stagework, it happened last weekend at Blair School of Music’s Ingram Hall with the world premiere of Marcus Hummon’s Surrender Road. Opera artistic director John Hoomes’ decision to stage this piece makes budgetary and logistical sense: it’s a small-cast affair; the technical challenges are relatively modest; only seven musicians are required; and, not least of all, the composer is a Nashville favorite son whose country-pop chart successes have paved the way for his more ambitious leanings toward musical theater. Hummon’s prolific, all right, and he can write a hummable tune with the best of them; for well over a decade, he’s been supplying major country acts like Wynonna, the Dixie Chicks and Sara Evans with hit material. But his aesthetic pedigree is a far cry from George Jones’. The son of globetrotting parents, he saw Africa before he probably even knew Nashville existed. He later attended Williams College, Stephen Sondheim’s alma mater. So when, in collaboration with Bill Feehely’s Actors Bridge Ensemble, Hummon began to produce a string of theatrical musicals, those who knew him could hardly have been surprised. Hummon’s previous stageworks, which include Francis of Guernica, Warrior and American Duet, have been at once admirable and frustrating. Beautiful music drives these efforts’ best moments, but the satisfying aspects are undermined by narrow plotting and serviceable but sometimes underdeveloped lyrics that thwart deeper  characterization. (American Duet is currently being considered for an off-Broadway run, having drawn wider interest in its story of bigotry against African Americans in the music business.) Writing for the theater is a different animal than churning out radio-friendly jewels like “Cowboy, Take Me Away.” While the three-minute song generally takes a single idea on a brief, colorful journey, a full-bodied theatrical venture will ideally tell a broader human tale by way of a strong main plot; adequately developed subplots; richer characterizations and story progression that emerge through tight lyrics; and a variety of musical forms that can range from a solo star turn to duets, trios, comic diversions and grand, statement-making group numbers. Where his musicals are concerned, Hummon has always insisted on doing his own thing without much regard for the concerns of conventional form or the input of other collaborators. These are wholly irrelevant considerations if his approach yields groundbreaking work, but Hummon has yet to show that he’s truly interested in doing what is necessary, lyrically and textually, to craft an easily identifiable show for the wider theatergoing audience. In 2002, he had the chance to make critical revisions to Francis of Guernica for its second production, sponsored by Tennessee Repertory Theatre. But even with outside dramaturgical input, Hummon failed to address the structural problems in his multileveled tale of the Spanish Civil War and the life of Pablo Picasso. There was some glorious music, though; if only that’s all there were to it. Now Hummon brings us Surrender Road, an 80-minute, 11-scene piece that might most accurately be described as a cantata in form, but with the spiritual sensibility of an oratorio. Michael Ching conducts the small musical ensemble featuring strings, bass, piano and Denis Solee’s soulful saxophone, all doing elegant justice to Hummon’s score, which is well fleshed out by Jonathan Yudkin’s classy and precise arrangements. Ron Kadri contributes a coolly expressionistic set evoking New York City, and upon it Hoomes stages the action with an eye toward the naturalism captured by the story’s predominant milieu: the fight game.   Barrel-chested tenor Hugo Vera plays Hummon’s protagonist, Manuel, an earnest boxer blackmailed into taking a dive. It’s an “I coulda been a contender” story, and Manuel is nothing more than a variation on Terry Malloy, straight out of On the Waterfront. Curiously, the program offers no direct clue as to exactly when this tale is taking place, but the noir-ish ambience reads like the 1950s, as does the boxing storyline, with its thugs and corruption. Vera’s a fine singer, and he receives solid support from tenor Richard Drews as Manuel’s trainer and baritone Alonzo Murphy-Johnson as a nefarious gangster. The love interest comes in the form of a struggling painter named Emily, played by Pilar Cragan. The Manuel/Emily romance is designed to drive the opera to its culminating point, and getting there might have offered more potential if Cragan had a big-time mezzo-soprano. She does not. She’s a quality pop singer with marginal acting talent.   Backed by a chorus of 19, the major players make their way committedly through Hummon’s music, which has classical aspirations—mainly in its exploitation of a hard-driving minor-key motif—yet still offers a gentle, toe-tapping pulse and the occasional uncontained pop feel, most successfully in the lovely ballad “Be Not Afraid.” Act 1 of Surrender Road is good enough to hold our attention in anticipation of a slam-bang Act 2 that never comes. The plot development challenges both credibility and audience involvement, in particular because Manuel’s plight comes off more pathetic than tragic, and Pilar’s sudden suicide seems contrived. The scenario, pitted with naive motivations, then devolves into a series of arias in which Hummon strains his controversial choice of working classic Shakespearean speeches into his libretto. Putting famous soliloquies from Julius Caesar, Hamlet, Macbeth, Merchant of Venice and other plays into the mouths of these socially marginalized figures dares to make a point about the universality of ennobled emotions. But given that the characters are otherwise speaking colloquial English, this device sounds more curious than enlightening, and to less forgiving ears it just smacks of self-indulgence or pretension. If Hummon doesn’t trust that his characters can express the necessary depth of feeling in their own vernacular, then it’s at the very least a risky proposition to expect the Bard to bridge the disconnect. The good music keeps us listening, but only quizzically engaged.    When they’re not quoting Shakespeare, the singers are also deserving of better rhyming schemes. Pop music gave up long ago bothering with true rhyme, yet it is the hallmark of genius theater lyricists like Oscar Hammerstein II, Cole Porter and Sondheim, who continually sought perfection in verbal meter and rhyme. In the opera house, where Hummon ought to be aiming high, he instead goes the route of Music Row hacks, rhyming “dream” with “thing,” “see” with “scream,” and “square” with “here.” Just because we’re in an age of sloppy craft doesn’t make it a better way to go—especially not in high theater. Hummon’s surely capable of such precision, but he never appears to work at it diligently.  Surrender Road was more than two years in the writing. It’s a viable idea, backed by gifted artistry, that gets hijacked by poor literary execution and a disregard for the elements of sustained drama. Hummon might as easily have set the screenplay of On the Waterfront to music. At least, then we couldn’t blame him for a weak book. As it is, “the fault, dear Brutus, is not in our stars, but in ourselves,” as Shakespeare so eloquently put it in Julius Caesar.