Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_5960 ( "Club" text, "Location" text, "Stadium" text, "Capacity" real, "Current manager" text )

### Question ###
What is the capacity for the stadium of kadrioru stadium and a current manager of sergei ratnikov?

### Accurate SQL ###

SELECT AVG("Capacity") FROM table_5960 WHERE "Stadium" = 'kadrioru stadium' AND "Current manager" = 'sergei ratnikov'