TORONTO — Before we get to the part that is certain to be sliced, diced and placed under an electron microscope — comments that will invite words to be read between their lines — it is important to know this: Paul Pierce is thoroughly committed to the Celtics and what they’re presently trying to do. Even with Rajon Rondo and Jared Sullinger down and out for the season, the captain still believes . . . even as he acknowledges the possibility that what comes next may not be conducive to his own goals and may force him to finish his career elsewhere.