Or you might look at it as "we have four vets and two still developing younger D" - Thrun is still developing and he's older than all the other prospects, while Lily is probably close to fully baked but he's still being given a shot to grow at 25. Walman, FWIW, didn't break out in DET until what, his age 28 season? Defense is hard. I'm not at all worried about any of the D prospects - the expectations are too high. Mukh is probably a Lily type guy and probably won't all of a sudden become a #2/3. So let him marinate. If he does become a 2/3 it's not going to be because we forced him into the lineup. Look at Thrun - he's bigger and stronger and older, not as skilled as the other prospects, but able to have passable games like last night where he looked like he belonged, at least.
That was Thrun, that's what they did with him. He's earning more ice time, but it has taken basically 2.5 years and he had AHL time before that. Last night Thompson got his shot and was holding on for dear life against a bottom feeder. He could still make it to 2nd pairing! But it's OK to let them marinate.
Warsofsky isn't going to solve our roster problems by rushing the kids to the NHL. it was already risky to do so with Smith, but fortunately he seems to be, also, holding on for dear life but at times showing flashes of top of the lineup play.