That grey area where it isn't clear whether or not you should report someone...
So I was just in a match, and one of my teammates disconnected. Was out of the blue, no apparent reason to leave (had a kill and assist, no death, no negative discourse in chat, etc). Pretty sure it was an actual unintentional disconnect, loss of internet or something (fun fact: that's actually a thing that happens sometimes).
At any rate, the disconnect isn't what brings up the grey area. The problem is that he was gone for almost 10 minutes. This allowed the enemy team to gain a significant advantage over us in team power. However, when he returned, he jumped straight in [and with some extra targeted support from myself] he caught back up and ultimately ended up playing a major role in our victory.
So you see the dilemma. Whether or not it was intentional, he did leave the match and almost outright lose it for us. However, he came back and we secured the win handily. I ultimately went with "not deserved", taking the aforementioned unintentional and redeemed nature of the situation into account, however I really don't know if a report is warranted or not in this situation.
EDIT: After watching the replay (forgot that was a thing we can do now), his disconnect was in fact unintentional. He had just finished wolf camp after a good gank, when he suddenly stopped moving and then "Teammate has disconnected!" announcement a significant period of time later.