Running back Reggie Bush described his first season in Detroit perfectly. “It’s been a roller coaster,” he said Friday. When Bush was on his game, the Lions soared. But when he struggled, the team often did, too. Bush’s season started strong, with 191 yards from scrimmage and a touchdown in a Week 1 victory over the Vikings. He also had three games with 100-plus yards rushing, and the Lions won all three. But, he lost a career-high four fumbles, and the Lions were 2-2 in those games. The losses came during the last six games when the Lions went 1-5 and fell out of playoff contention. He also missed 2½ because of injuries, and the Lions lost two of those. “Ultimately, I always put the team first, so my team goals always come before my personal goals,” he said. “Obviously, if we didn’t accomplish our goals, which was to win the division, make it to the playoffs, Super Bowl, all that stuff, then we have a lot of room for improvement.” And because Bush signed a four-year, $16 million contract last offseason, he’ll be around for whatever improvement comes.