I’m sorry to hear about your disappointing season. We hear his refrain often which is why I wrote this https://uphillathlete.com/death-by-threshold/
I would strongly recommend strength training during your base training. What you want to avoid in your strength workouts is high intensity interval still circuit training or what we call Muscular Endurance workouts. They will make heavy metabolic demands and those demands will mostly be met by glycolysis with elevated lactate levels. This will for sure impede your rebuilding of your base. Conventional strength training with is more neuromuscular in effect with 2-4 sets of 2-8 reps will not make big metabolic demands. We use the strength methods mentioned in both our books during the base period even for those with severe ADS and we see good gains in aerobic capacity.