While pitchers continue to shuffle to the shelf in The Bronx, two of the Yankees’ high-end, upper-level right-handers made progress this week in the early stages of their minor league seasons. Brett Marshall, the organization’s No. 6 prospect in Baseball America’s rankings, sputtered through his first four Triple-A starts for Scranton/Wilkes-Barre, compiling a 7.36 ERA and 14 walks (with 19 strikeouts) in 18 1/3 innings. The sinker-baller, a 23-year-old Texas native, said the key to a turn-the-corner outing Thursday, when he hung up seven shutout frames at Gwinnett, was getting back to the basics of his go-to pitch. “The past few starts I was trying to force ground balls, instead of believing that the ground balls would come on their own,” he said, according to milb.com. “I was focusing more on just commanding my fastball until my pitching coach [Scott Aldred] said I should throw the sinker more. I’m getting my confidence in it again, so that’s definitely a good thing.” Jose Ramirez, who turned the head of none other than Mariano Rivera in spring training with a high-90s fastball and severe changeup, had his Double-A debut delayed nearly a month by injury, then came out of the bullpen in his first appearance for Trenton last week. In his first start Wednesday, the 23-year-old Dominican yielded just one hit (and one unearned run) in five innings while striking six and walking one.Mets April misfits Kirk Nieuwenhuis and Josh Edgin continued to struggle after changes of scenery. Nieuwenhuis, playing regular center field for Triple-A Las Vegas, produced a .200 average (.371 slugging) and 11 strikeouts in his first eight games.