Highlights from Davey Martinez’s media availability from Citizens Bank Park on Wednesday… Keibert Ruiz’s [Lack of HR] Power [So Far]: “I think he needs to stay behind the ball better and use his legs,” Nationals’ manager Davey Martinez earlier this month when asked what catcher Keibert Ruiz needed to do to hit for a bit more power. “And they’re working with him on not jumping out. Like I’ve said, he’s got really good bat-to-ball skills, now we just got to get him to let the ball travel a little bit and let him use his lower-half a little better, and…