I can't really say he's improved on the ground. Sure, he didn't get subbed, but Kang looked pretty bad in that fight, and he pretty much let Mousasi slap on that triangle.
I just don't see him becoming the next big MW. A solid MW? Sure, but the next big MW? No, not yet. He has some solid wins under his belt, like the Hector Lombard win (And Kang if you want to include it), but I just don't see it yet.
I thought Kang looked far from stellar. I'd say that he looked pretty damn pathetic towards the end of that fight, just letting Mousasi slap on a pretty meh triangle.