A senior-year drop-off in academic performance sends a bad signal.
That is why an upward trending grades are a big positive. Some students struggle with the transition to high school and the trials of teenage years. Some just don’t develop good study habits until they have a little practice at it. Poor grades in the first years of high school will weaken your record, but not as much as during your junior and senior years. If your grades continually improve throughout high school, admissions counselors will be encouraged that you’re on the right track.
Admissions counselors are evaluating your application to get a sense of where you’ve been and where you’re going. They will look at how you chose to spend the last year of high school. This is to see whether or not they think you’re taking the next step towards college.