Who said his losses got to him beyond reason? He punched some kid in the face after he tried to kill everyone? Boo hoo. His losses are the only reason why he knew how important that baby was, how Carver needed to die, and how Jane's irreverence was unreliable to the point of being dangerous. Oh yeah, he's also the one who delivered the baby.
I don't see a single action of Kenny's that wasn't necessary outside of his Arvo abuse getting a teensy bit out of line.
In the same way some see choosing Kenny as crazy, that's the way I see Jane too.
Over the whole season? I can think of plenty, including 1 that got 1 (possibly 2) people killed and another that got Luke killed. He would of let more die, if it wasn't for Sarita/Clem likely being the next target. Unnecessary actions, since you can't save a group by yourself with a bolt-action rifle when your enemies have semi-automatics. Another potential issue was when he was going to try to break out, but luckily got knocked out in the back of the truck.
Jane wasn't crazy, just irrational on her later plan. That is the only action she done wrong that qualifies her as crazy. Only other problem with her is she was surviving to survive and not truly living. She was justified on what she was trying to do, but it was a crazy plan, no one denies this.
Everyone knew how important the baby was... how does marching for Wellington (don't go by gamer eyes here) blindly, aide the baby? It was blind hope and could of left the group in ruin. That is not how to lead a group.
Only things he did right that I completely agree with is killing Carver and leaving Arvo behind. He never thinks anything through and acts with impunity, just like in S1.