On Saturday night, one left the performance of Verdi's "La Forza del Destino," with which the Metropolitan Opera finished its two-week run at the Kennedy Center, just a little baffled at why the Met had bothered to bring this production on tour.

In the three main roles--each a major plum in Verdi's vocal legacy--the singers Saturday night suffered from serious handicaps. Additionally, one got the feeling that very little attention had been given to how they would interact dramatically.

Otherwise this "Forza" was eminently creditable, as would be any performance with James Levine in the pit. And when the action turned to the Franciscan Cloister of the Madonna degli Angeli, to which all the protagonists in this tale of family betrayal and revenge turn at one time or other, the monks brought the evening's one touch of vocal glory. Bass James Morris' sonorous and somber Padre Guardiano was the one performance that was up to the lofty standards that the Met has set for "Forza" over the years.

In the magnificent duet with Leonore, while trying to convince her to enter a convent, Morris' mastery of Verdi's grand line made it all the more clear how far soprano Leona Mitchell has to go in becoming a real Leonore. This is one of Verdi's greatest roles, and it would be foolish to expect a singer as new to it as Mitchell to have caught its full measure. The characterization is now rather stiff, with little sense of the mental turmoil--the mix of ecstasy and guilt--that haunts Leonore.

Mitchell has the notes, though at present the voice is a bit small, and the wealth of color and shading that make a great Leonore are simply not yet there. Once in the evening, though, Mitchell captured that quality for a moment. It was at one of the grandest moments in the opera, in the ceremony of dedication that ends the first monastery scene, when Leonore breaks out in the prayer "La Vergine degli angeli," that Mitchell caught the rapt soft mood memorably.

Tenor Ermanno Mauro's difficulties with the part of Leonore's lover, Don Alvaro, were just the opposite. He showed a real sense of how to color and shape this wonderful music, but he just couldn't harness his shaky vocal resources to do the job.

One could only sympathize with British baritone Peter Glossop in the role of Leonore's vengeful brother, Don Carlo. He had been brought in with little preparation time to sub for the ailing Sherrill Milnes. Even then he gave the most credible performance among the three principals. He had easy theatrical presence, and his singing, while not as rich as Milnes', was assured and sophisticated. One could only feel for him when the evening's claque, which had been screaming bravos for practically every mediocre moment, greeted his splendid performance with indifferent silence.

Isola Jones was a respectable Preziosilla, but played the tart a bit too much like a mezzo who made a wrong turn on the way to a performance of "Carmen." Renato Capecchi was an amiable Fra Melitone.

The men's chorus sang especially well in the first monastery scene. And throughout, the chorus was splendid, though it sometimes lacked the precision that extensive rehearsal would have allowed.

"Forza" was Levine's ninth performance in 14 days. It was typically cohesive and vigorous. It is truly amazing.