At its core this fight is wrestler vs wrestler and you normally would just pick the better wrestler. In this case the better wrestler also happens to be the better striker. I think Mansur is twice the athlete, 5x the wrestler, 10x more powerful and I think he cleans up here. The one and only concern would be actually BJJ skills, but that would only matter if Klein can make something happen in a scramble which I don't think he can do. Mansur is the very confident pick
Nick Klein
Nick Klein is a solid grappler with rangy striking. When he is striking he likes to stay on the outside and pump jabs and leg kicks to keep you at distance. He will eventually take a shot and does a great job lowering his level and shooting clean takedowns and then transitioning into BJJ. On his feet he can be a bit soft and uncomfortable but on the ground he is a grinder and definitely at home. He is making his UFC debut after a contender series win.
Mansur Abdul-Malik
Mansur Abdul-Malik is a very good grappler with college wrestling experience. He fights as you would expect a D1 wrestler to fight. He comes forward, throws heavy and then wrestlers. His takedowns are big and clean. He does a nice job lifting when he needs to and has great control on the ground. He also has great elbows from top and will work. He is coming off the KO win over Dusko Todorovic in his UFC debut