Had an awesome summer, 100+ mpw average for 3 months (previous high average was like 80) and was PRing like crazy off very few workouts (Old XC PR was 16:33 and went 15:30 in my season opener). Had one awesome workout the next week and then my tempo was hard to maintain 5:50 pace for 30 min. The next week I had a decent K workout of 6x1000 @ 3Thresh/2CV/1VO2 and hit pace, but then raced that weekend and barely broke 18 for 5k, feeling aerobically depleted and having 1 gear when I can usually negative split like crazy. My mileage dropped from 115 for my peak to low 90s with faster workouts. What's wrong??