SAN FRANCISCO – Though Pat Spencer’s rise from Warriors bench-warmer to legitimate NBA impact player comes as a surprise to most of the world, his veteran teammates already had seen enough to believe it was possible.Count Stephen Curry, having observed Spencer for more than two years in Golden State, as a ground-floor believer.“It’s amazing to watch,” Curry said Thursday after practice. “We’ve seen it over the summers, in practice, when he’s been out there in short spurts. He just has a presence about him that he just knows the game. He plays with 120 percent of confidence every time he’s out there. And as a kind of playmaker role, it was cool to see him kind of adapt to what we needed pretty much overnight. And I think it’ll only help us as we keep moving forward.”As Spencer was bringing welcome intensity to the Warriors last week, Curry was a distant observer. He remained in the Bay Area to rehab what he described as “a (quad) contusion that combined with a muscle strain,” but he took note of Spencer – making his first career starts – taking a leadership role in victories at...