The biggest scare right now for Caddy has got to be, as mentioned above, the number of carries he's getting.
Rookies generally hit that "rookie wall" about week 10, and here we're talking about a guy that's never carried the load before getting more carries than almost any player, not just rookie, has ever gotten.
They're going to have to lighten his load or he's going to end up in a wheelchair by year 3. It's my guess that they'll realize this.
Then the question becomes how effective is he? He had 158 yards last week, but on 37 carries. How often is he going to get 37 carries? Not very. What happens if he only gets 22-25? I believe he was around 24-79 at one point during the game, likewise in week 1 he was 25-69 at one point. What if that's the end of his carries and he doesn't get 27, 28, .... , 37 because his coaches realize they can't ask a guy to carry 490 times a year.
All that said, his keeper value is super high right now, and it's quite justified.