There were no surprises in last night's program at the Jewish Community Center in Rockville--except, of course, the program itself. A capacity crowd came, as it usually does to the center's well-run "Artists of Excellence" series, and it left clearly satisfied, as is also usual. But instead of hearing Shlomo Mintz playing violin music of Beethoven, Prokofiev, Bloch and Ravel, it heard Santiago Rodriguez playing piano music of Debussy, Beethoven, Chopin and Liszt, with the "Spanish Dance No. 5" of Enrique Granados as an encore.

Mintz phoned the JCC yesterday afternoon, only a few hours before his scheduled arrival, to offer his regrets; he was ill and unable to perform. A frantic search for the nearest international-caliber soloist who might be available quickly zeroed in on Rodriguez, who lives in Adelphi, Md., gives more than 100 performances per year in the United States and abroad, and happened to be home with not much to do. "I wanted to get out of the house, anyway," he said when he was asked to substitute.

It was not the dramatic "a star is born" story so popular in musical folklore. Rodriguez is too well-known for that and his performance was merely very competent, not mind-boggling. But he has a fine flair for the standard repertoire, a technique that meets all the established criteria, a good sense of musical form and, most important of all, a firm grasp of what makes audiences happy.

One could quibble about occasional points of tempo and dynamics in the "Appassionata" with which he ended the first half of his program, and the revisionist school of Debussy interpretation might prefer that he use just a bit less pedal in the four Preludes he played. There are always grounds for complaining (if one is so inclined) about vulgarity in a program that ends with Liszt's Sixth Hungarian Rhapsody. And it hardly needs to be pointed out that a program including all of the above, plus Chopin's Ballade in G minor and Scherzo in C-sharp minor, is rather lacking in originality. Against all of this, it must be noted that most of the people who bought the tickets loved every minute of it and that Rodriguez did it all very well, with virtuoso technique and a clear sense of the variety of forms and styles he was presenting.

The textures in his Debussy were nicely varied, with gradations of finger pressure calculated to the milligram. He played the "Presto" in the "Appassionata" prestissimo, as is the custom, the Ballade flowed with a nice sense of poetry and the essential contrasts in the Scherzo were properly underlined. He managed to get a feeling of soulful song into the slow passages of the Liszt and to set a countermelody into proper relief at the work's climax. We have heard it all done equally well by others, because our age is blessed with a lot of fine pianists. But it is good to know that we have someone in the neighborhood who can do this sort of thing at this level on a few hours' notice.