I was always told that you should expect you grade average in college to be one grade level lower than it was in high school. A-average students in high school are B-average students in college; B-average students in high school are C-level students in college. Quiet frankly, this is just a reality of life. You are entering into a much more difficult, condensed, pressured atmosphere where the work is more difficult and the time you have to do it is limited. For the first year or two, there is an adjustment period which causes students' typical expectations for grades to decrease.
In college, it’s commonly understood that an average, mid-level grade is a C. You can earn a B by showing deeper-than-average thinking, organization, and style skills. A’s are reserved for the most excellent, insightful, sophisticated, and engaging writing. Getting As is not impossible, but it does require a lot of sacrifice, time, and effort.