Football players notoriously score worse during/after the season because:
1) they are not training specifically for the CFA in season - yes they are in good shape, but their workouts are focused on achieving optimal performance for their position, not the spectrum of events on the CFA
2) the weekly games and practices tend to leave your body battered which degrades overall performance - a bruised hip here, a bruised shoulder there, and you aren't scoring optimally on all the events.
That doesn't even get into the worst case scenario which is a serious injury like a torn ACL that prevents you from taking the CFA before the deadline and thereby disqualifies you from admission for the year. While you could recover in time for Beast and get the medical waiver, you won't have a shot because you didn't have the 6-9 month recovery time between the injury and the CFA and fail to complete the application.
Finally, waiting until the deadline in general to complete your application is always the wrong answer.
1) it delays the overall file review and qualification which means that the admissions officer/RC won't look at your file and let you know if there is something that you need to improve to be competitive and/or if you need a medical waiver, it won't go forward until you are complete. The RC has a lot less leeway in who they request a medical waiver for later in the admissions cycle and there is a greater chance your medical waiver won't be complete in time for admission decisions late in the cycle. Med waivers take on average 90 days from the date of request. File completion. Deadline is the end of February, Medical decision deadline is normally mid-April which is less than 90 days from the application deadline.
2) waiting/delaying shows a lack of interest or priorities that lay elsewhere - something you definitely don't want to convey to your RC when there are more than enough of highly qualified candidates competing for the same spot.