Really, there are a few schools of thought when it comes to the first round of the draft.
Best Player Available- This is the theory that you just rank the players from 1-250 and take the guy that's at the top of your list every time it's your turn to pick. Sounds good in theory, but it's rarely done based on this principal alone.
Best Player Based on Team Needs- Also good in theory because there's really not that much separation between 2-3 players at any point in the draft, but it can lead to reaches and over-valuing players while trying to fill holes on the roster.
Best Value- This is where you try to maximize your dollars spent by trying to get a player in the first round at one of the higher paying positions (QB, RB, WR, CB, LT, DE) for much less than you can get a comparably priced player in free agency. Best bang for the buck, especially if it also matches BPA and/or team needs.
Best Production- This is the theory that you have to get production from your first round pick. Although it flies in the face of reason when considering the other above options and the fact that going from college football to the NFL is usually a huge step for these players, it is a valid point and many subscribe to it.
So really, it seems like the best bet for TT and the Packers is to try and find a player in the first round that meets as many of the above criteria as possible.
BPA- That'll be up to the players available when they select and how they have them rated.
Team Needs- I would think that RB, S, WR, TE, DE, CB, FB and OL would be high on their list in this category.
Best Value- Seems like RB, WR, CB and DE would meet this criteria as well as filling a team need.
Best Production- With questions at both the RB and WR positions, it seems like a legitimate talent at either the RB or WR positions would get ample opportunity for playing time with the Packers this year, so it stands to reason they would also offer more production.
So back to your question as to taking a 1st round RB, it certainly seems reasonable to me as far as meeting all the above criteria, that is as long as they have one rated that high when it comes their time to pick. It also has the added value of being a position where most teams are utilizing RBs by committee nowadays instead of relying only on a star back as teams used to do.
All-in all, I wouldn't be that disappointed with a good RB taken in the 1st round.