Chris Mullin didn’t change. Not even slightly. He remained upbeat and positive, refusing to listen to the growing swarm of criticism. He showed up for work every day believing in his players, guaranteeing them their luck would eventually turn if they continued to work hard and listen to the coaching staff. It turned over the last week, first on Saturday and again Wednesday, in the form of two hard-to-believe upsets of Duke and Villanova, two national championship contenders that were each favored by double-digits and feature a significant number of NBA prospects. Suddenly, the team that was finding new and inventive ways to lose games is somehow figuring out how to beat the best teams in the country. And Mullin, the legendary alum in his third season as coach, has keyed the turnaround. “[He deserves] all the credit. Coach is [there] for all of our guys,” junior forward Marvin Clark II said shortly after the stunning win over No. 1 Villanova, St. John’s first victory over the top-ranked team in the country since 1985, when Mullin was a player. “All he’s been preaching is, ‘We’re right there, just stay together, stay close. We have opportunities ahead of us. We still have more games to win.’ ” St. John’s was close during its 0-11 start to Big East play, losing eight games by seven points or less, coming painfully short of upsets of Villanova, No. 5 Xavier, Seton Hall and Creighton, arguably the four best teams in the league. Most importantly, Mullin never let the players see him down despite the difficult setbacks, multiple sources within the program said. He arrived each day with a positive mindset. In film sessions, when he pointed out what was missing, Mullin did so in an encouraging manner. He illustrated how close they were to being a winning team and getting on a roll.