Much of the Rams’ focus this offseason involved the addition of offensive weapons. First came the free-agent signing of tight end Jared Cook, formerly of the Tennessee Titans. Then, in the draft, the Rams selected Tavon Austin and Stedman Bailey, a pair of productive big-play receivers from West Virginia University. The draft also yielded a power runner in Vanderbilt’s Zac Stacy. The team also improved its offensive line with the additions of Pro Bowl left tackle Jake Long via free agency from Miami and three-time national champion guard Barrett Jones from Alabama in the draft. In a matter of months, the Rams were transformed from a team built around the power running game of Steven Jackson, a free agent who signed with the Atlanta Falcons, to an offense loaded with explosiveness. Not forgotten but somewhat overshadowed by the Rams’ many offseason additions is second-year receiver Chris Givens, who came on strong after a slow start last year to catch 42 passes for a team-leading 698 yards and three touchdowns in 2012. A fourth-round draft choice out of Wake Forest, Givens also led the team in kick returns, averaging 23.4 yards on 24 returns. And he set an NFL rookie record with five consecutive weeks with a 50-yard pass reception. “That doesn’t bother me at all; all that’s going to do is help me not get doubled,’’ the 22-year-old Givens said when asked about being overlooked. “I really don’t pay attention to that too much. As a team, we know who we have and know who’s going to make plays, and I’m one of those guys. I’m just trying to come out here every day to get better.’’ Givens, who played at 6 feet and 198 pounds a year ago, spent the offseason working to get stronger “to be a better all-around football player.’’ Givens even referred to himself as one of the squad’s ‘older’ guys.