No he is not a pure striker. He has collegiate wrestling experience and he is at least a blue belt in Brazilian Jiu-Jitsu.
Your correct on his fighting style though. He uses his wrestling to avoid takedowns. If he is taken down, he uses his wrestling and Jiu-Jitsu skills to work to get back up.
As for Cintron, he could use his wrestling to try and avoid a take down and to scramble for a stand up if he was taken down. The hole in his game would be his submission defense. If he has no training in that, he would probably be submitted before he could scramble back up if the fight went to that ground.
Hope this helped answer your questions.
Correct in that Chuck isn't a pure striker, not even close. He has a VERY solid wrestling backround, including a good college career. His striking style comes from a base in Kempo karate, and kickboxing. Chuck has a brown belt in BJJ too, so he's not gonna be clueless on the ground...not even close. He chooses to keep his fights standing because he's had a distinct advantage over the other guys at LHW in the UFC in that department.
As far as Cintron learning good takedown defense, well, easier said than done. Learning to avoid takedown, while still fending off strikes is not something you learn overnight. Many of these guys that do this have been training for a VERY long time. Cintron's wrestling is nothing special either, and it's not gonna help him against Sherk who is a BETTER wrestler. He placed 10th in state in High School, that's not that big of an accomplishment, but beyond all that, he hasn't even been training in wrestling for quite sometime. Besides, what's he gonna do, take Sherk down? I highly doubt that would happen, but if it did, it's not like Sherk has never been there before. He was on his back for 25min with Matt Hughes, whose probably one of he most brutal GnP guys you could have on top of you. The adverse will most likely happen, with Cintron on his back, some place that's totally foreign to him. When you're on your back, getting elbows slammed into your head, while trying to avoid submissions, the game changes quite a bit. This fight would look something like this....they come to the center of the cage, circle eachother, Sherk shoots in, picks Kermit up, slams him on his head, starts smashing his face in with elbows/punches from gaurd, and either passes his gaurd, only to end the fight with strikes, or he submitts him easily.