The Nets have assembled a roster full of big names and expensive contracts. Now it’s up to the players to make it all work. That was the message repeated over and over again by Paul Pierce, Kevin Garnett and Jason Terry — the trio of veteran Celtics acquired in the blockbuster trade that was agreed to last month — during yesterday’s press conference at Barclays Center to introduce them to their new home and fans. “You see the talent that’s already here, and you see us coming into it, and now it’s about how well we gel, understanding one another and understanding each other’s games,” Garnett said. “I felt like the difference in the years we spent in Boston when we won was just how we dealt with each other, and how we communicated with each other. “That sounds like little things, but it’s the little things that make up nights when you’re down and you come back and you make a run. ... You have to communicate, you have to understand each other and it’s about how well you gel. That’s going to be the biggest question mark for this team: how we’ll be able to gel and how quickly we’ll be able to gel.” With Pierce (35), Garnett (37) and Terry (35) having a combined 47 seasons of NBA experience, it’s clear this group wasn’t put together to contend three or four years from now. The goal is for the Nets to immediately launch themselves into the championship discussion after the team’s first season in Brooklyn ended in a first-round playoff exit at the hands of the Bulls. In