How am I still able to move??

I've been riding my bike a lot lately and going to a lot of baseball/softball practices. Doing all of that and the combination of not stretching except for during the warm-ups have made my muscles extremely tight. I've never been the most limber person and have always been borderline tight but it's getting quite embarrassing.

In class we've been practicing doing initial assessments on each other and one of the tests are muscle length tests. Just comparing the results from last week to this week I can feel that my musles have seized up. How is it possible that I'm not walking around like a robot or maybe I am and no one's saying anything...