SAN FRANCISCO – Losing the Robin to the Warriors’ Batman was a big enough blow. But being without a generational talent and all-time great for two months has kept the Warriors’ offense stuck in the mud all too often.Since Feb. 1, the Warriors rank 25th in points per game (111.3), 24th in field goal percentage (45.9 percent) and 26th in 3-point percentage (33.7) for a 111.4 offensive rating, which ranks 23rd in the NBA during that span.To barely beat the 17-win Brooklyn Nets on Wednesday night, the Warriors did shoot 52.9 percent from the field, yet they were hamstrung by 26 turnovers and a 33.3 percent 3-point percentage. Generating easy offense has to be the priority without Steph Curry, Jimmy Butler, Moses Moody and so many others.That’s where the free-throw line became the Warriors’ best friend against Brooklyn, and why they need to be frequent visitors to the charity stripe, straying away from their past trends.“If you can get to the line, it just sets everything up,” Warriors coach Steve Kerr said Thursday after practice. “You get easy points and it sets your defense up. So, it’s a big deal....