For most of the Trojans’ practices this spring, senior quarterback Matt Barkley has been without his top playmakers because of injuries.Tuesday offered a glimmer of optimism for the Heisman hopeful, thanks to the return of sophomore wide receiver George Farmer and a pair of tight ends — redshirt sophomores Xavier Grimble and Randall Telfer. Although the three only partook in limited portions of practice, their improving health was pleasant news for an offensive unit that has struggled at times to establish a passing game this spring.Injury bug · With injuries depleting the offense, senior quarterback Matt Barkley has had some rough stretches in practice. He said he is still focused, despite not throwing to his most reliable players. – Corey Marquetti | Daily Trojan“Once we get back into the swing of things — it’s been kind of rough with guys injured, Marqise [Lee] doing track — we’re going to get into a flow,” Barkley said. “[I’m] still teaching the young guys some stuff, but I’m not worried with myself, my game or my decision-making.”ωBarkley’s reference to not worrying about his performance thus far comes as a result of an uncharacteristically high number of interceptions during spring practice, an anomaly USC coach Lane Kiffin attributed to his quarterback possibly “getting a little bit bored” as other quarterbacks grab extra reps. Barkley, however, didn’t want to go that far.“No, I’m not bored at all,” Barkley said. “I’m staying in tune with what we’re doing, staying mentally involved. And when I’m in, it may be a little frustrating at times just because it’s not clicking like you expect it to be, but I just think it’s an opportunity to improve with tough situations.”ωBarkley and the rest of the quarterbacks were treated to a couple of extra receiving threats for passing drills — 2009 graduate and current Tennessee Titan Damian Williams, along with 2008 graduate Patrick Turner, who most recently played for the New York Jets. The two were a welcome sight as Farmer, Grimble and Telfer inch toward a return to the field.“I just saw Damian Williams and Patrick Turner out there and I was loving throwing to them,” Barkley said.Kiffin was glad to see the former stars as well.“We’re still down on receivers, which is why we tried to help our quarterbacks out today by bringing out Patrick and Damien, which was good to see,” Kiffin added. “It was another example of Trojan players helping each other out. [It was] good to have those guys out here.”ωOn the defensive side of the ball, Kiffin was quick to compliment junior safety Demetrius Wright, who he named MVP of Tuesday’s practice.“Demetrius has really shown flashes throughout the spring,” Kiffin said. “He had a good day today, really dominated special teams drills early on too. He’s becoming more consistent.”ωKiffin was also complimentary of Wright’s new secondary coach, Marvin Sanders, who is charged with the task of re-shaping a unit that finished 101st in the country in passing yards allowed last season.“The whole secondary is improving,” Kiffin said. “I think that has a lot to do with Marvin being here, and doing a really good job with those guys. And you can see their individual development on and off the field.”ωAlthough the Trojans are improving health-wise, they are still without redshirt freshman tight end Junior Pomee, redshirt freshman running back Buck Allen and junior wide receiver Robert Woods. Pomee, who left practice last Thursday with what appeared to be a serious injury, did not break his right foot as originally feared. The team will be cautious with bringing him back, however, as he missed the entire 2011 season after injuring the same foot.