McCaffrey is gonna get his head knocked in if he isn't careful. Dude is way small. This ain't college anymore, son, you gonna get knock around harder than ever before. If he's gonna last and be effective, he needs to take a look a Sproles, since he resembles him in more ways than one.
Best Rookie? That's a tough one. Your first instinct is to go with someone drafted high, but it's usually someone in the mid rounds that steals the show (like Dak last year). I guess I'd go with Fornette since Jacksonville really has no other really good RB on their roster. The #1 overall guy could be a stud, as well as the LB the 9ers got at the end of Round 1. It's really a crapshoot though.
What about best Rookie QB? Watson is obviously gonna start for better or for worst in Houston. Mahomes and Tribisky, I believe, will rest all year and study the game; no need to throw them into the fire unless a key injury occurs. I think Beathard from the 49ers might be a surprise Rookie QB. He had 2 TDs in his first preseason game, and since he only has to beat out Hoyer and Barkley, it wouldn't be hard to become the starter. Those two will screw up enough to give him the job,at least bythe end of this year and for this season. Still gonna go with Watson though for best Rookie QB.