Trade help please

I was offered this trade in my league.  I was offered Doug Martin and eric decker for Steven Jackson. I currently have RB- Arian foster, Steven Jackson, Demarco Murray and Cedric Benson and WR-Dez Bryant, Kenny Britt, Jeremy Maclin, Titus Young and Micheal Crabtree.  Its a standard pts league.  Any thoughts would be appreciated.

how many people do you start in each position. Decker gives you depth at WR and I would do the trade if you only need to start 2rb. Martin is solid, Jackson is better, but Decker can be utilized during certain matchups.

Need to know more to confirm the trade.

starting lineup is 2rb, 2wr and a flex