Over the last three games, Helu's gotten 15, 10, and 12 touches, with 4 touchdowns. Morris has been at 16, 16, and 19 touches. Two things to consider: 1) this was after Kyle Shanahan said they wanted to get Helu more involved, and 2) Morris's carries have also trended up as the Washington offense has rounded into shape.
The result is that both RBs have value. Helu isn't just a consideration for flex duty this week; I think that particularly with the injuries that have hit the FF landscape that he's a great Rb3/flex to roll out there in upcoming weeks, especially with the Washington defense struggling to contain the opposition. They face plus offenses against Denver, San Diego, and the Eagles in three out of the next four weeks. Those all look like good matchups.
Morris got knocked out of the Oakland game with hurt ribs in that first 16 carry game listed. Helu took over for him, and that was the first game of the season that Helu got extended play. I've noticed in the two games that have followed, Morris will signal to the sideline for a breather. Morris and Helu both have their strengths.
Morris is a better between the tackles zone runner, and he has better vision to make cuts. He also gets better as the game goes on. Helu is better catching the ball, and he can accelerate quickly with his speed. His speed works well against opposing D's when they are tired, or to catch them off guard. Then there is Griffin lll who also is going to run the ball. Morris and Griffin are the primary runners, and Helu will continue to be the third down back, and the back used as a receiver when they are catching up, or want to catch another team off guard with his speed (like they did at the GL last game). I think Denver is second against the run, but Washington can mix it up with their running game so maybe they will have some success.