It's amazing that fans who've watched this whole Belichick era still have annual panic attacks about position groups before the seasons even start. Every year there's a perceived hole somewhere on the roster and every year fans go crazy about it, until it inevitably works itself out - and fans move on to the next thing to freak out about.
This goes all the way back to the Bledsoe era. Remember David Terrell? We supposedly needed receivers in the worst way then. Remember also that people were furious that BB wasted a draft pick on a quarterback when we had three already?
Remember how people were panicking about the nose tackle position before the Ted Washington trade? How people were furious we drafted Nate Solder when we already had Matt Light under contract and needed pass rushers?
Then there was last year, when we needed corners so badly, and we watched one draft binky after another go elsewhere. Now we are more stacked with young corners maybe than we've ever been.
BB is a weird dude for sure. Absolutely it would seem having a three-down threat like David Johnson would be nice. But for whatever reason, they don't seem to care. That's probably because of their experience solving the RB problem with guys off the scrap heap. From Lewis to Woodhead to Green-Ellis to Jonas Gray to Blount, they seem to end up with enough guys to win without spending either money or much draft capital on the position.
This is also a team that constantly cycles through the bottom of its roster, before and after the draft. Does anyone really believe they won't keep bringing backs through?
Personally I love the Lewis-Blount combo, when healthy. I'm guessing Donald Brown, who actually has been good in the NFL before, won't embarrass them if he has to play in the interim. This is nowhere near as bad as the year they cut all their safeties a week before the season or whatever. In only a few cases (the infamous 2006 WR corps being an example) did any of these position-group panics ever turn out to really cost them. They find players and coach them up quick and that's one of the fun parts of being a fan of this team, frustrating as they can be sometimes.