Not sure you and others are giving Walker enough credit for his improvement over the season at running between the tackles. Yes at first he was skittish and bounced to the outside a bit much, too predictable for a while, and yes, sometimes he fails to run through arm tackles or tackles a bigger back would shed. Walker really works on his craft with dedication, and I (personally) saw growth and improvement over the year.
The "stuffed runs" stat you shared was a great find, and it would be interested to see that stat for say, the last 4 games, or for half the season. Walker does have trouble running through DL and LB tackles because of his smaller size, but is amazing at breaking or eluding DB tackles downfield. The counterpoint was that Walker did have a few "man-size" runs, including one shorter TD run that gave me flashbacks of the amazing Chris Carson, so possibly there are some adjustments that Walker or Waldron, in play-design, play-calling, can make to have fewer stuffed runs while still getting Walker's home-run gift.
If anything, I sure hope we see plenty of K9 in mid-3rd quarter and 4th quarter, against tired defenses, where a fresh Walker is breaking tackles from tired players who would have brought him down in the 1st or 2nd quarter. Charbonnet will be key in wearing down those defenses in quarters 1-3. Charbonnet may get more carries than Walker against certain teams, e.g., 49ers and vice versa. In my mind, the important thing is to share the workload, keep both backs healthy, and have a stable of 2 or more good backs available come postseason. Walker, or Charbonnet, isn't that a high-quality problem to have?