Trump has no ads running during his convention. This is unusual. The simplest answer is that he has a major cash flow problem, especially relative to Biden. https://twitter.com/NYTnickc/status/1298769579599163394

The reason Trump is off the air in places like MI is because Biden will never allow Trump to outspend him there, and the cost/benefit analysis doesn't work for Trump to keep increasing the spending when he's underwater in so many other states.

Biden will get to $200 million this month, and will be in the $100-$150 million range in Sept/Oct. He'll have enough money to saturate the close battlegrounds and go for some gravy states.

Biden is doing to Trump what Obama did to Romney. Obama hit Romney early w/ads, but he also ramped up spending early & didn't stop. Romney was never able to get economies of scale or ad spending that was orders of magnitude higher to beat an incumbent in states he won in '08.

Trump was 7-10 points down in MI out of the gate & hasn't had a significant number of outside groups spending $ (or as strong support from the Russians, the #buttheremails MSM or the FBI Director). He needs to spend a lot of $ to get into contention & Biden keeps upping the ante.

However, MI isn't the only state where he's had problems. PA/WI/MN are also tracking to 2018 results, and WI is actually tracking back to Obama 2012 (and slightly better?) margins. AZ is tracking better than 2018 and there are no weak base states for Biden.

In addition, there is a significant regression to the mean happening in OH with IA also knocking on the door of reliving the 08/12 glory days. Dems also have a strong Dem party in NC that can win grind it out elections. Put that all together and you see why Trump is an underdog.