Orioles manager Buck Showalter wouldn't rule out the possibility of Chris Tillman in the Opening Day rotation. "I've really been impressed with his stuff,'' Showalter said. ''Tilly's a guy with a big upside. I feel good about where he is. His arm is a lot further along than it was last year at this time." Reporting to camp in ''noticeably better shape,'' Tillman has allowed just three runs in 8 1/3 innings in three spring games.