Running backs are the core of any fantasy football team. So which teams drafted a workhorse running back to lead their franchise for the next five to ten years? Which teams drafted guys who have to fight for playing time? Here's the list of draftees that will be immediately taking over the starting tailback duties for their team:

May outperform McGahee this year: Bills RB Marshawn Lynch
After trading away Willis McGahee the Bills needed to draft a running back and everybody in the league knew it. So Marshawn Lynch (Buffalo, 12th overall) takes possession of the starting role (Anthony Thomas, exit stage left) and becomes an immediate fantasy star. Lee Evans is one of the best receivers in the league and QB J.P. Losman continues to improve so Lynch won't be expected to do everything by himself.
The offensive line wasn't great last season, finishing 26th in the league with 47 sacks allowed and the Bills haven't done much to upgrade the line in the offseason. The performance of the offensive line has been blamed for Willis McGahee's sub-par (990 rush yds, 6 TDs) stats last season but there's evidence that maybe the problem was McGahee. In the three games that McGahee was hurt, backup Anthony Thomas rushed 67 times for 260 yds (3.9 avg) and 1 touchdown. Those stats aren't too bad considering Thomas was a journeyman running back on his third team in three years. If those are the stats that Thomas can put up, a full season of Marshawn Lynch should produce numbers around 1200 rushing yds and maybe 8 TDs. Lynch is also adept at catching the ball out of the backfield so that provides more fantasy value.
And...that's it. Only one running back taken out of this year's draft will be starting without sharing time. No, I didn't forget that other guy - brand new running backs who will be sharing time are coming up later...