My two cents.
In FBB building a FBB roster around injured players, rookies, and international guys is not tanking IMO. It's smart roster management for a rebuilding team. In the NBA, teams like Orlando, Phili, and Boston took the NBA equivalent approach.
In FBB, this approach starts to enter a "tanking" gray zone area when the GM has the Lamar Odoms and Delonte Wests of the world on their roster. IMO this is just lazy and bad GM'ng. With a little planning, research, and general activeness those deadbeat NBA castoff could have been 2013 #1 picks like Livo Jean Charles, Sergey Karasev or Solomon Hill. These rookie aren't playing, but are/were on the waiver wire (LJC is overseas, but is a player listed Y!). One or two may develop into a player while Lamar and Delonte will never play in the NBA again.
Not setting lineups / leaving a team's best players on the bench IS tanking and should be dealt with severely. NBA teams do occasionally do this, but not often. In fact, given the Epic-ness of this year's draft, I can't recall one case of a NBA team tanking this season.
In FBB, it's out of control. I am in 4 keeper leagues and this year's be awful. I am hoping it's just b/c of this draft and will disipate next year.
Example:
One unnamed GM in one of my full-keeper leagues did not set his roster for more than a month and was very spotty for a month or two before that. This was abominable considering how stacked and mostly healthy his roster already is. This was easily recognizable tanking and irritates me to no end.
Mk