It wasnt too long ago Trump was well ahead in Wisconsin. He lost this one because he is such a nasty and negative individual. All he talks about anymore is “lyin Ted Cruz”. He no longer brings up anything positive anymore. So he lost a lot of support. Those 15% losses to Hillary in the polls hurt too.
You are right: Trump probably doesn’t follow the advice he is given, and it shows. People were saying what happened tonight was going to happen around Labor Day, but they were all just premature. There is still though more likelihood of a Trump nomination than not, but his margin is growing dimmer.