Torrey Smith for sure, he's go to guy in the long passing game in Baltimore and I see him putting up some nice numbers this week.
Alfred Morris I feel is a bad play this week, I think alot of people might play him in flex spots this week but I don't expect a repeat of week 1 numbers.
That leaves a tossup between Richardson and Greene in my opinion, I might lean a little towards Richardson just because I'm always scared to play RB's against Pittsburgh D (are they even still that good against the Run though?)
I would go with the same advice as above. Start Smith for sure, that's a no brainer. I would never start a Shanahan RB no matter how good he was the week before. And between Greene and Richardson, I respect the Steeler D more, making my choice Richardson.