With a rotation that is a largely a mixture of aging veterans and somewhat unproven starters, Phil Hughes’ health is not something the Yankees want to worry about. And while the right-hander still has several tests to pass before he can be counted on to begin the regular season in the rotation after last month’s back injury, yesterday was a positive sign. Hughes threw live batting practice for the first time since suffering two bulging disks in his upper back on Feb. 18. The 26-pitch session went according to plan, but he’s not ready to make any guarantees he’ll be on the mound in time for the first week of the regular season. “Everything has to go right,” Hughes said after he finished throwing at George M. Steinbrenner Field. Hughes reported no problems and, if he doesn’t suffer any setbacks, is scheduled to throw a simulated game Monday. “I felt great and the ball was coming out pretty good,” Hughes said. “I was excited because I haven’t done it in so long. I hadn’t faced a hitter since last playoffs.” And Hughes’ arm strength has nearly returned to where it was before the injury.