SPRINGFIELD, Mass. — Antoine Mason scored 21 points, Juan’ya Green added 15 and top-seeded Niagara pulled away from Siena 74-62 Saturday in the quarterfinals of the Metro Atlantic Athletic Conference tournament.The Purple Eagles (19-12) built a nine-point lead with 5:51 to go until halftime, but the ninth-seeded Saints used a 12-4 spurt get within 32-31.Marvin Jordan’s trey opened the second half, then Mason scored seven straight points, capped by a three-point play with 17:19 left, to give Niagara an 11-point lead.Siena (8-24) came back again with an 11-2 run to make it 44-42 with 12:19 remaining, but the Saints could get no closer.