Orioles manager Buck Showalter spent much of Friday afternoon telling players who will and won’t be making the club’s 25-man roster — leaving him with only one decision remaining. Steve Pearce and Conor Jackson are still battling to be the final first base-outfield reserve on the club’s 2013 roster. Otherwise, things are set for Tuesday’s season opener, with right-hander Jake Arrieta winning the final rotation spot, lefties Brian Matusz and T.J. McFarland added to an eight-man bullpen and infielder-outfielder Ryan Flaherty capturing a utility role. “Yeah, it’s definitely exciting news,” said Flaherty, who, as a Rule 5 pick last year, was with the Orioles all season, but can be sent to the minors this year. “To be able to help the team out, it was kind of my goal coming into camp, and I’m excited to get the opportunity.” The roster picture became clearer this week as starting pitcher Chris Tillman (abdomen soreness) was placed on the 15-day disabled list Thursday, while infielder Wilson Betemit (right PCL tear), right-hander Steve Johnson (right lat strain) and left-hander Tsuyoshi Wada (recovering from elbow ligament surgery) will be put on the DL this weekend. Betemit’s injury cemented Flaherty’s spot on the roster, while McFarland benefitted from the club’s decision to disable Tillman, who will be eligible to be activated April 6 and is expected to start the fifth game of the regular season.