This is accurate especially with the warm-ups. Research shows that one of the most sure ways to injure a muscle is to do passive stretching. Hence the dynamic warm-ups you described.
I don't think any of these issues is related to the in season activities. It's all about what type of training they are doing in the off season. Similar to what you described. What are you training for, strength is great but there needs to be functionality. A basic principle od training is SAID, Specific Adaptation to Imposed Demands. If you don't train for explosive running out of the box, your body won't be able to handle it.