Ummm, your information is a bit off. Lets correct it.
1) Anderson is not a rookie. He was in his 3rd year when he signed that contract with Houston. Hence, not an example of a commonplace "rookie signing a long-term minimum contract mid-season"
2) Green was not a rookie when he signed with the Spurs. He was drafted and played a full season with the Cavaliers and was cut (out of training camp) going into his second season. In addition, he didn't sign a long-term contract when he did sign with the Spurs (it was for the remainder of the season with a non-guaranteed second year).
3) It is not uncommon for "scrap heap players" (be them rookies, or discarded players like Anderson or Green) to a two year deal, with the second year being fully non-guaranteed. This was likely the case with Da'Sean Butler and Malcolm Thomas. Of course, the first year is also non-guaranteed, meaning they can be cut early in the season without any serious issue. This was also the case with Derrick Byars, whom the Spurs signed last year, carried into TC, and cut.
4) Better examples of unusual signings are as follows:
DeJuan Blair: Draft pick signing a four year deal with a lot of guaranteed money on the front end, a lot of non-guaranteed on the back end.
Hassan Whiteside: Draft pick signing a four year deal, first two years fully guaranteed, second two years non-guaranteed (he played two years, was cut, and is now in the NBDL)
Gary Neal: Undrafted free agent, rookie, signing a fully guaranteed minimum deal out of Summer League for 3 years