As you will find, this has extensively been discussed due to lightning strikes and unsafe conditions on the tarmac for the below-the-wing personnel. So, none were on the tarmac to aid planes at the gates, and as time stretched on, more and more arrivals worsened the problem -- as the closest diversion airports were no better. It was not a manager problem.
Could it have been handled better, maybe, but I certainly don't have that information and knowledge, perhaps some here do. Note that during the afternoon / early evening, ATC stopped all aircraft movements from time to time. There will certainly be an FAA/DOT review of what happened at a half dozen major airports yesterday, as the situation was as bad or worse elsewhere.