Orioles left-hander Brian Matusz’s five-inning, one-run outing on Tuesday against the Boston Red Sox in Fort Myers continues to make this spring battle for the No. 5 rotation spot tight with less than two weeks to go in big league camp. On Tuesday, Matusz was very aggressive in pounding the strike zone. Both Matusz and Buck Showalter agreed that Matusz probably was too aggressive and needed to try to bury a couple more sliders while ahead in the count to keep hitters off balance. Another interesting aspect of Matusz’s success is his 4.33 strikeout-to-walk ratio (13 strikeouts, 3 walks) this spring. “[That’s] very important, being able to prevent free bases,” Matusz said. “The strikeouts will come with being able to make quality pitches. The walks are the big thing. To be able to let the defense play, especially with the guys we have back there. We have a solid defense, so just being able to attack the zone and working ahead in the count.” His outing against the Red Sox was his best of the spring yet. It wasn’t as dominating as his last start against the Twins, in which he struck out seven and threw four hitless innings, but he was able to get key outs in critical times -- something he struggled to do sometimes as a starter last season. Five of the first nine Boston runners reached base on Matusz, but he was able to hold the Red Sox to one run and then began to settle in a bit. Then he got out of a fifth-inning jam with runners at the corners with one out, which was the difference between a solid five-inning outing and a so-so 4 1/3. After the game, Showalter said something pretty interesting. While everyone might believe that Matusz’s late-season success in the bullpen means it makes sense to have him open the season as a reliever, Showalter said he’s not assuming Matusz will have the same success there this season. “It’s not a given,” Showalter said. “I’ll be frank with you that if he hadn’t had the success in the bullpen, we probably wouldn’t be having this decision. It bodes well for him as far as his ability to make this club in some form. It does have something to do with some of the thinking. “I do not look at it as a bird in the hand that he’s going to be as successful in the bullpen as he was last year. He’s done nothing to make be think he wouldn’t be, but I think this is the time of the year when you get in a lot of trouble if you assume something just because it happened last year.”