Standards-based grading creates a poor education environment for students. For example, students could previously get an A+ for understanding all of the content needed. But with standards-based, students can only achieve a 3, or an A- if they understand all of the content. They need to go "above and beyond" to get better grades. Standards-based grading statistically lowers student GPAs, which means students could be drastically less successful, which could negatively impact their selection of options for their future. 

Standards-based grading also positively affects students' grades who don't deserve good grades for the work put into their class. For example, knowing the basic content of a subject could allow a student to achieve a level 1, which is about the equivalent of a D, but in reality, if they barely know much, they deserve a low F.

Lastly, standards-based is a very difficult concept for students to grasp on a large scale. If everything is graded using standards, it will be hard for students to know how they are doing overall in school. The gradebook would become less user friendly, and students can easily comprehend their grades using the letters A, B, C, D, and F.

Hopefully this speaks to you, and helps you understand how negative of an impact standards-based grading will have on the school district.