Champion Reworks

I really would like to know what goes into deciding which champions get a rework and who makes those decisions. The recent rework of Shen got me thinking the other day. I still don't understand why he needed a rework when he got so much high-level play, especially in the LCS. So why did he get the rework attention over other champs that, in my opinion, need a rework way more.

Other Champions that I think NEED a Rework:

1. Aatrox
2. Taric
3. Warwick
4. Yorick (I realize Taric and Yorick have upcoming ones, I just don't know why Shen got one before either)

Champs with less of a need but maybe one just to get them more attention:

1. Fiddlesticks
2. Galio
3. Singed (I would of added Nunu on this list but I don't know if he's that bad/unfun)