The same exact thing happened to me for the last 3 years. I found that I was coming into the season ill equipped to handle the high volume of workouts our coach had us do from day one. I would usually run OK in the first few meets, but then fall apart when it counted. I was pushing all the workouts as hard as I could, but just didn't have the base to handle this and properly recover from day to day. It got to the point where I was completely fed up with my coach's training plan and had zero faith in it, which obviously helped contribute to the poor performances. We did have people who ran great on this workout plan, but they were the ones doing 100+ mile weeks all summer and thus could handle 3-4 hard workouts per week plus a full race schedule.
Finally, this year I took matters into my own hands and trained like a man over the summer, running way more quality base miles than ever before. When I got to school I did the workouts way more relaxed, only really hammering in 1 or so per cycle and even sandbagging the ones which I felt would make me unnecessarily tired. I allowed myself to actually recover, and thanks to my summer training was strong enough to really kill the vital workouts. In short, I came in strong and tailored the workouts based on how I was feeling, always listening to my body. I recently ran a pretty substantial PR, and am planning on training hard way further into the season, because in years past I would cut my mileage way, way too much during championship season and would feel totally flat as a result.