Vazquez was among the top pitchers in the National League last season, but has struggled a lot this year. He's 9-9 with a 5.05 ERA in 23 starts and has not won in five outings.
Vazquez says he's disappointed in Tuesday's decision. The Yankees also skipped him for a start in May. He will be available in relief on Wednesday.
Nova made his first major league start against Toronto on Monday night, allowing two runs and six hits in 5 1-3 innings.