I don't think there's any question Ben would be considered a better athlete than Tyreke...but maybe there should be.
We have a tendency to associate "athlete" in an NBA sense with run fast, jump high. And you know what? Very few guys in the NBA are going to run faster and jump higher than Ben. But that's not all there is to being an athlete. There is strength (if the comparison is Reke for instance, Reke wins that easily) lateral quickness (from what I've seen also quite possibly Reke), reach (Reke), etc. etc. And more importantly in a basketball sense, how much of an athlete you can be with the ball? That's the difference between them. Ben's a great run/jump athlete without the ball. With the ball? He really can't do much. So in an offensive sense most of his great athleteness is wasted. Its pretty much going to get him an alley oop or two a game, and then make him a strong runner/finisher on the break, again as long as he isn't having to handle it himself. Those are bonuses and should give him a couple of extra hoops a night if he gets minutes, but its not like a LeBron situation where you have a dominant athlete who's also dominant with the ball. That's where a great athlete can just be impossible to guard.
Sans ballhanding ability, being a good athlete actually may have more direct application on defense than offense. That's why even though Ben has been getting lit up there is talk of his "defensive potential". Basically he's a very good athlete with apparently a good attitude and hence you expect he could be a good defender in time, largely just because he is superior physically. The only real red flag I see on that front is how quickly he moves laterally (as opposed to forward and back, where he's exceptional) -- lateral quickness is actually maybe the most important guard defensive trait. It would be the wrong thing to be lacking.,