Let me explain what the Trump strategy SHOULD be and will give an analysis of several important thresholds that the media never talks about. The media never talks about them because they are too stupid to figure it.
The media acts like these future primaries all happen in a vacuum and one does not tie into the other. There is an important point of inflection that will occur that I think will have a major psychological effect on the race. We know that Ted Cruz is well behind Trump but still has a slim chance of securing 1237 for the convention. We know Kasich is out of it but hanging in. The important point of inflection is the point when Ted Cruz has been mathematically been eliminated from securing 1237. When that occurs Trump should pounce on that and ensure all Cruz supporters know that he is eliminated. Trump should even make a pitch that Cruz should drop out, although I doubt he would. It still weakens Cruz substantially. It won't boost Trump's support but there will certainly be a percentage of Cruz supporters who stay home in future primaries.
Trump's strategy should be to eliminate the possibility of Cruz securing 1237 as soon as possible. Wisconsin goes a long way towards achieving that goal. Now it looks like Trump will lose Wisconsin, and possibly lose it badly. That will be tremendous blow to Trump and you will hear the media echo chamber blasting Trump for 2 weeks leading up to New York. Trump is polling at 54% in New York. He needs 50% to secure all New Yorks delegates. If the momentum lost in Wisconsin causes Trump to get less than 50% in New York, Trump is in major trouble.
Think about it like this. Your football team is up by 21 midway through the 3rd quarter. Your quarterback throws a dumb interception and you shrug it off because, hey you are up 21. By the time the game is over, your team has lost. You think about what went wrong, and say the game turned with that interception. Wisconsin is going to be Trump's interception. Get it?