Disagree there. Anyone could play solid defense...but great defense is something else. I think it takes great physical frame (tall enough, strong enough, fast enough to guard anyone) and great instincts. Sure anyone can be solid...but great? There are always few great defenders. I think of Paul George mainly, Iguodala, Smith is pretty good...some of these guys are lazy at times too like Rondo and Smith so defense is not that much about effort. Sometimes players just don't know what they are doing, defense is mostly a mental thing...again instincts, experience, knowing what your opponent likes to do. That's how some of these old guys stay in the NBA.