He played deep safety as well in Cincy. He wasn't Earl Thomas out there but he also wasn't terrible.
As for Heath, he's not that great a center fielder either. He's often slow to react and see plays develop, etc. He has average "feel" out there during games as well. It's peculiar that people are so defensive of such an average to below average player here.
But there were people who defended Nick Hayden too despite the evidence he wasn't very good.
I try to be fair to all players instead of letting biases taint my viewpoint. Heath is a decent starting free safety and a poor starting strong safety.
His coverage skills have improved greatly since he was thrown out there as a rookie from a small school. He was often out of position that year and late getting to the ball. He shouldn't have been starting any games, but injuries and a lack of depth pushed him into the lineup.
Most fans seem to still see the Heath of 2013. Too slow to react, poor recognition. However, he has developed over the past few years in those areas when it comes to playing the pass. He made a major step forward in 2016 as primarily a deep nickel/dime safety, which is the reason Dallas tapped him to replace Church as the starting strong safety. Playing out of position in 2017 got fans back on his back and made some of them have blinders on when Dallas switched him to free safety, where he played well for the rest of the season. Being back at strong safety last year moved him away from what he does best and justifiably brought back the criticism.
You seem to be an all-or-nothing fan — either you like a player or you don't — who can't see that players can be pretty good at one thing while being pretty bad at another. Heath is a pretty good coverage safety. He's not great and he's upgradable, but you can easily do worse in that role. He's not very good as a run-support safety, which is sadly the role Dallas has him in.
I'd prefer that he go back to being a deep nickel or dime safety.