The Yankees are still figuring out their third base situation with Opening Day starter Ryan McMahon struggling mightily at the plate.But until they do, McMahon will be riding the bench. Manager Aaron Boone's lineup in the team's series opener with the Royals has Amed Rosario starting at third. What makes that notable is that Michael Wacha, a right-hander, is on the mound for Kansas City.Now, Wacha is a neutral right-hander in his career, but it shows how poorly McMahon has hit -- and conversely, how well Rosario has performed -- that Boone would rather have McMahon come off the bench.Boone's decision is more about matchups over the next six games.

After Wacha, the Royals will start two southpaws and the Red Sox series should feature two lefties as well."This is probably a stretch [where he won't start] and he's working on a lot of things behind the scenes that I actually feel like I'm seeing some progress on," Boone explained. "We need him and expect him to be a real factor for us, not just defensively but offensively as well, so with these next several matchups being a little more difficult, probably be a lot of Rosey in there. While McMahon continues to kind of work through it."Boone didn't commit to Rosario starting all three games of the Royals series.

The skipper revealed there will be lefties in the lineup against Cole Ragans on Sunday because of the reverse splits, but he hopes this stretch allows McMahon to continue to work behind the scenes. So what is McMahon working on?"More, just kind of staying more square with his shoulders. He can kind of rotate that front side, which kind of gets him in and out of the zone a little bit, and I actually feel like he's making some progress on it.

Again, he's really talented offensively. There's real juice in the bat. There's knowledge of the strike zone. Hopefully, we can get him to a better place ....we need his production, especially down at the bottom of the lineup."So far this season, McMahon is 5-for-42 (all singles) with two RBI and eight walks. Rosario is 9-for-34 with a double, two home runs and six RBI.