My experience for several years was that I would go hard in the early season, and inevitably sustain some sort of grievous injury that would mean a summer of rehab, only to recover once the outdoor meets were basically done.
Badly torn hammy, huge deep bruise on adductor, strained quad, severely sore and clicking achilles, etc..
Last year, it was achilles/heel problems due to new flats that didn't work--inserts solved the problem.
Funny, something different each year, but returned to good health and good form, only too late for meets!!!
The one common denominator seemed to be the transition to outdoor training, and possibly getting too explosive too quickly.
This winter I'm working on my aerobic and lactic systems, in the hope that I will better be able to recover from the jump in training intensity by clearing toxins more efficiently, and by just working my body more, by doing more reps of everything. Hopefully that will build some biological tolerance for the inevitable training step-function.
Why not just smooth out the step function? Too hard, and I don't notice it until it's too late. For instance, all is usually fine until the next morning, when the grievous injury manifests. That's what you get for running without a good coach!
So far, so good. Am beginning to work in plyos now at the start of Feb, and to increase weights from a sort of "idling" level to actually trying hard.
So, try building good base, and get a good coach if you can.