Should I trade Vernon Davis TB (TE) for D. Williams for CAR (RB)?

This is my fantasy football team. I need to know if I should do this trade or not.

QB

M. Vick (PHI)

J. Flacco (BAL)

J. Culter (CHI)

RB

D. McFadden (OAK)

F. Gore (SF)

E. Graham (TB)

WR

D. Bowe (KC)

S. Holmes (NYJ)

M. Colston (NO)

N. Washington (TEN)

P. Harvin (MIN)

TE

V. Davis (TE)

F. Davis (WAS)

DEF

DAL

CLE

MIN - I am dropping soon. They were just a fill in for two weeks ago.

Should I do this because my rbs are bad. I drafted N. Moreno because John Fox was the coach but he is doing bad so I cut him when he got hurt.