Tight end Jared Cook wants to be a difference-maker with the Rams. And it seems the team is more than willing to give him that chance. Cook, 26, certainly looks the part. At 6 feet 5 and and 248 pounds, he runs the 40 in 4.49 seconds and is versatile enough to play on the line, in the backfield, in the slot or even out wide. His combination of size, top-end speed and athletic ability enables him to stretch the field and create matchup nightmares for opposing defenses. He was the Rams’ first big-ticket purchase of the offseason, signing a five-year, $35.1 million deal less than three hours into free agency. Cook, who played his college ball at South Carolina, was drafted by the Tennessee Titans in the third round of the 2009 draft and enjoyed two unspectacular seasons while playing for Jeff Fisher. Following a bit of a breakout season in 2011, when he caught 49 passes for 759 yards (15.5 per catch) and three touchdowns, Cook — and the rest of the Tennessee offense — fell off last year, when he finished with 44 catches for 523 yards and four scores. In 2012, the Titans ranked 22nd in passing yards per game (207.7), 23rd in completion percentage (58.9) and 27th in passing touchdowns (17). “That offense really didn’t suit me,’’ Cook said . “It didn’t fit me. That’s just how it is. Every team a player goes to, the fit is not perfect. Some guys have to move around to two or three teams before they find the perfect fit.’’ But Cook, who was also pursued by the Miami Dolphins, likes what he has seen so far in St. Louis. “I think I’m on an elevator going up,” he said in his first meeting with the local media. This will mark the third and final week of offseason workouts for veterans at Rams Park, with the rookies sticking around for another week. Fisher likes the overall progress that the team has made and has been impressed with Cook’s play. “What we’re getting from Jared out there is what we expected,’’ the coach said. “The ball’s going around, we’re matching him up, we’re creating mismatches, he’s making plays. “Whether or not (he was underutilized with Tennessee), we feel like he can add a dimension to our offense that we don’t have.’’