Not sure who has them as the top backs, but NFL.com (which I have found to be most accurate as they have the most access to NFL scouts and player personnel execs) has the top backs as:
1) Brooks (6.38, #33 overall)
2) Jaylen Wright (6.28, #54 overall, one spot behind Edgerrin Cooper)
3) Benson (6.19, #89)
4) Lloyd (6.18, #95)
5) Tracy (6.18, #96)
6) Estime (6.17, #97)
7) Irving (6.17, #98)
8) Shipley (6.16, #109)
9) Corum (6.15, #111)
10) Guerendo (6.15, #113)
If that's around how things play out, they probably won't be available for the Packers in the 4th.
I think part of what is contributing to some rankings of RBs on some sites is that many of these players (Brooks, Wright, Lloyd, Tracy, Guerendo, and to a lesser extent Benson and Estime) weren't on the radar pre-season because they weren't starters the year before or weren't 1,000 yard rushers the year before.