Just looking at the game logs for the three primary RB from 2014
Doug Martin
This is really unremarkable performance aside from two games late in the season against Carolina and the Saints. He missed game 2 and 3 early on in the season and then games 8-10 in the middle of it.
In the season opener Martin goes 9 carries for 9 yards against Carolina then misses the next two games. After he returns Martin does not get more than 15 carries until game 12 against the Bengals which was a close contest. Martin gets 18 carries 58 yards and a TD.
Martin had 20 targets in his 11 games which is 1.8 targets/game
Bobby Rainey
Rainey only missed one game over the course of the season.
Rainey filled in for Martin during game 2 and 3 when Martin was first out. He had an excellent game week 2 against the Rams and then in game 3 against the Falcons, he isn't used as much as a runner, but does catch 7 of 8 targets for 64 receiving yards, giving him 100 combined yards in this game. After this Martin comes back his performance falls off after that until week 8 where he gets 19 carries for 87 yards. game 8 is also the first week Martin missed after coming back in game four.
Rainey is used more as a receiver than Martin. He had 45 targets which is 3 targets/game
His targets in the passing game fall off after Sims returns in week 9. 31 of the 45 targets occurred while Sims was out. Rainey does get 5 targets in game 9 against the Falcons (1st week Sims is back) and 6 targets in game 11 against the Bears but seems to be behind Sims for that role after this.
Charles Sims
Due to Sims injury he does not see action until game 9 of the season. He does not get used much as a runner until the
final game of the season against the Saints where he had 18 carries for 69 yards and a TD.
Sims had 27 targets during those 8 games which is 3.4 targets/game
In total there were 93 targets to RB in 2014 which was 17.8% of the total targets. Sims had the most targets/game out of the three RB