SAN ANTONIO - In a postseason full of firsts for this young San Antonio Spurs team, they got their first chance to close out a desperate opponent in Game 5 against the Portland Trail Blazers. The Spurs were on their home floor with a chance to advance to the next round and prevent a return trip to Portland, but the Blazers were quite resistant to the idea of their season ending. San Antonio knew that would be the case, so they hit first and then weathered the storm before delivering the knockout blow. Earlier in the week, Lakers coach JJ Redick provided a brutal but perfect metaphor for what makes a closeout game so difficult. "Well, you have to kill them," Redick said with a deadpan delivery. "You have to kill...it's difficult to kill someone. Survival instinct says 'I want to stay alive.' So you've got to be able to kill them.” On an academic level, the Spurs knew this to be true. But Tuesday night was the first time they faced the task of killing a team that desperately wanted to live.…