I'm no Southee hater but he does seem to be better suited to the longer forms, particularly red ball, and should never be given the ball at the end of a white ball match. Lockie might be better, or Milne.
Sorry - I was responding to this bit of your post, and we've had posts cross in electron land.
Arguing he gets smacked at the end (he did) doesn't mean he shouldn't bowl. He's been very very good in white ball cricket for a while. Honestly, his pace is up as well - mid 130s is better than he used to manage!
But yeah, gets smacked at the end. Some of that is the match situation too ... but I wouldn't be dropping southee on his current form