Nets point guard and two-time Olympic champ Deron Williams showed off his gold medal in Brooklyn this week. Three days after leaving London — and teammates Carmelo Anthony, LeBron James and Kobe Bryant — Williams headed to the new Barclays Center to show his medal to construction workers finishing the arena before Jay-Z’s opening-night concert Sept. 28. Williams has become a familiar face: He’s visited the Nets’ new home five times since construction began.