PORT ST. LUCIE — Long-shot fifth starter candidate Jonathon Niese threw three hitless innings in a minor-league intrasquad game here this morning. Niese was forced to throw against prospects to get his turn because the Mets are off today and didn’t want to adjust the rotation. Niese threw 48 pitches, walking one and striking out one. He said he spent part of the time working on his changeup after getting tips on that pitch from guest instructor John Franco.