It's harder to play Safety in zone than it is a man. In man you're just helping, the CB is doing all the hard work.
Regardless of talent, man is almost always gonna force tighter throwing windows. I would rather play man and risk getting beat deep than play OUR version of zone, which allows teams to nickel-and-dime us all the way down the field.
Either way, it's not just a man-vs-zone issue with this defense. It's THE WAY we do things. That's the problem. Our zone is the prehistoric spot dropping variation. We just cover grass and don't match up with routes.
When it comes to man coverage...
I don't/wouldn't call man coverage unless I'm sending heat. It's hard to play man if you're not putting pressure on the QB.
The Miami Dolphins have the best 3rd down defense in the NFL, and it's cause they heat MF'ers up and play man coverage. The Dolphins will send 6/7 guys and play Cover-1 or Cover-0. The ball has to come out!
Even when Baker/Manny blitz, a lot of time they play zone behind it. This often leaves somebody open.
If you're creative, there's ways to prevent yourself from getting beat deep when you play man.
When heating it up...
If I play press-man there's really only 2 routes that the offense likes - vertical/fade or slant. (or screens) There's generally not enough time to throw anything else if you're sending heat. Shallow crossers and stuff like that take too long to develop. When Baker/Manny scout an offense, they can observe what said offense likes to throw when they get press-man blitzes. If they like to throw fade, prepare your CB's to play press-bail. If they like to throw slants, emphasize taking away the inside. If you're worried about an inside quick slant, drop one of your D-linemen into the throwing window.
If you're worried about them beating you deep then play off-man when you send heat. In off-man most offenses will try to throw slant. But when playing off-man, you have your DL and LB's walk up to the line-of-scrimmage like they're all coming, then drop 1 or 2 of them into the hook/curl zone when the ball is snapped. Now you're taking away any hot/quick inside routes while also preventing the deep ball.
EXAMPLE - first play of this kid's highlights...
Football is a game of chess and we ain't even trying to play it.