You ask if Michel is an expert in Ukrainian corruption? Let me repost how his focus is on kleptocracy and grand corruption developments in the post-Soviet space.
"I'm a writer, analyst, and investigative journalist on topics ranging from kleptocracy and grand corruption to developments in the post-Soviet space and Western relations therein. I received my Master's degree in Russia, Eurasia and Eastern Europe Studies from Columbia University's Harriman Institute, and my pieces and analyses have appeared in outlets like Foreign Affairs, Foreign Policy, The Atlantic, The New Republic, POLITICO Magazine, Washington Post, Sports Illustrated, Just Security, Bellingcat, ThinkProgress, Quartz, The American Interest, Organized Crime and Corruption Reporting Project, openDemocracy, Guardian, National Review, World Politics Review, Al Jazeera, Slate, The Daily Beast, Roads & Kingdoms, Talking Points Memo, EurasiaNet, Houston Chronicle, Jamestown, Moscow Times, Radio Free Europe/Radio Liberty, and Business Insider, among a host of other outlets. "
http://www.caseymichel.com/
Edit: let me add more from Michel’s bio:
“ I recently put together a full-length report with the Hudson Institute on the U.S.'s transition into a global offshore finance haven, and I’ve spoken at both the Atlantic Council and Wilson Center’s Kennan Institute on kleptocratic tools (shell companies, anonymous trusts, etc.). I'm a member of the Advisory Council for the Hudson Institute's Kleptocracy Initiative, and I also recently served as a Senior Investigative Fellow with the Human Rights Foundation.”
Go ahead and disagree with his conclusions, but it is utterly hilarious to try and say that he doesn’t have an expertise in what I said he does.