On Sunday, Musk tweeted that he was working on a "secret master plan, part 2," with details to come later this week. The cryptic announcement sent shares about 4 percent higher Monday.
"I'm not sure exactly what's happening here. What we do know is that earlier in the year, Elon and the full management team really emphasized that they were focusing on execution and generating operating cash flow," the senior research analyst for Oppenheimer said in an interview with CNBC's "Power Lunch."
Since then, the first-quarter results were OK and there was disappointment surrounding Tesla's delivery numbers in the second quarter.
"Then a real shift in strategy as they've decided to … accelerate production on the Model 3, change course and buy SolarCity, and now this mystery event," he said.
While he wouldn't speculate on what Musk's plan is, Rusch said he wants to know more about the SolarCity deal and the future of the company.
"Our objection to the SolarCity acquisition — and we downgraded the stock after that was announced — is really the use of capital at Tesla. … The real metric we want to look at is how much money are they investing and what's the return on their capital."
Tesla has been under scrutiny lately for that deal, falling short on its delivery guidance and for two car crashes that may have involved autopilot.
Rusch said this sort of crash was inevitable.
"You've got a new functionality which is changing operator behavior, and our view is that there was at some point going to be a problem that was going to have to involve regulators, and there was going to be more regulation."