Pretty much every corner in the league is now. That's why most corners have wildly fluctuating grades year over year now days. They rules are stacked against them in the modern NFL.
Every qb goes through a slump if they get enough starts. Every single one. Mahomes has not until now so it's a little jarring for the fanbase. People need to chill, they'll figure it out.
Why would you need to play 2 high against a rook making his first start at qb. That's lunacy. Mix up and disguise your coverages and confuse the shit out of him while committing to stop the run.