We carry 4 running backs (not counting special teamers or fullbacks). HOPEFULLY, they last four years each. Belichick isn't picking up 5th options.
So, we need a new RB every year, and more if the RB's don't last four years.
So, by your measure, every patriot running back is terrible since Belichick continues to draft running backs. The reality is that we have a revolving door, by choice.
Michel is doing exactly what he was drafted to do. Harris is doing just what he was drafted to do. White has done much more than we have any right to expect. Now, we add Stevenson to the mix, probably in a minor role, as is unusually the case for rookies if the starters are back.