Two minutes of half-assed stretching can do a 'tight' muscle more harm than good. Think about it. What would happen if you took a plastic bag, grabbed it at each end and stretched it out as hard as you possibly could? You'd get a thinned out, stretched, weak plastic bag for your efforts.
Now think about doing the same thing to your muscle tissue. Then think about the effect that stretching your muscles and then heading out for a couple of hill sprints will have on your body. I'm guessing you wouldn't be surprised to know that it's probably not the best course of action.
Ok I'm lying. It's not like a plastic bag being stretched. After all, your body can withstand a hell of a lot more than you realise. But what stretching does do is inhibit muscles from working to their full potential. And doing that BEFORE exercise is only going to cause problems (unless there are certain muscles that you actually want and NEED to inhibit).
So, what we need to do is take the haphazard brutal stretching out of your routine and replace it with the intention of improving your range of motion as a system. Through daily mobility exercise, foam rolling and the exercises that I give you during your biomechanics assessment, you'll prepare your body so much more.