Can a game be labeled big without a week of the schedule complete? In the Yankees’ case there was no other way to view yesterday’s 7-0 victory over the Tigers in front of 39,829 at Comerica Park. Sure, they downplayed the significance of a win on April 7 because that’s how managers and players are wired. Still, they entered 1-4, were facing Justin Verlander, perhaps the best pitcher in baseball, and had ace CC Sabathia going for them against arguably the top lineup in the game. Lose a second game inside a week with Sabathia pitching and the gloom and doom would grow thicker. Much has been made of Sabathia’s declining velocity since he barely touched 92 mph Opening Day against the Red Sox. It was more of the same yesterday for the large lefty but expertly mixing in 84-mph sliders and 78-mph change-ups, Sabathia provided seven shutout innings in which he allowed four harmless singles and only faced one batter with a runner in scoring position. “My fastball command was a lot better and the change-up was working early,’’ said Sabathia, who explained locating the fastball inside produced different results from Opening Day when he gave up four runs and eight hits in five innings. “I pitched in a lot more.’’ How important was it for manager Joe Girardi to get out of Motown with a win? He used Mariano Rivera in the ninth with a 7-0 bulge. Jayson Nix, who started for a second straight game at short for Eduardo Nunez (bruised right biceps), went 3-for-4 and hit a two-run homer in the three-run third off a 3-1 Verlander change-up. “I had one hit [in 11 at-bats] against him, a single, and it was on a change-up,’’ Nix said of Verlander, who pointed at his head with an index finger as Nix rounded the bases.