A ballet company is forever a work in progress. Wouldn’t it make all the difference to give us at least one major revival of a big, full-throttle Balanchine ballet that hasn’t been seen in a while? Something to test the prowess and artistry of the company’s several remarkable younger principals? Isn’t it time for new casting in “Chaconne” and “Mozartiana”? When will “Tchaikovsky Piano Concerto No. 2,” “Raymonda Variations” or “Harlequinade” return? Will the new production of “Symphony in C” bring new casts as well as new costumes? isn’t Mr. Martins too cautious about exposing his best dancers to the highest challenges?