Btw, kudos to those men, they have richly deserved it for some time now. I know Frank pretty well and he's an amazing creative mind.
Anyway, asymptotic freedom is the key feature of the Strong interaction that makes it manageable mathematically.
Technically it has to do with something called the beta function in field theory, and how the renormalization group flows to negative values.
But somewhat less accurately, if you move quarks arbitrarily far apart, the force that wants to push them back together goes off to infinity.
Basically that says, you will never find a free quark in nature. It also
says, if you throw a particle at a conglomerate of quarks, then to good approximation you dont have to deal with them at all, but rather the composite particle (like say a proton) uniquely. So that simplifies our life tremendously.. Many body problem --> 1 or 2 body.