I thought Yandle was fine b/c it was a cheap one year deal.
I didn't "love" TDA, thought he was a good gamble but an overpay.
You're basically gambling that coming home will motivate him to keep his nose clean, not that he'd totally forget how to play defense (i.e. not that he was ever good, as JFresh showed, neither is Ghost, but he was never this bad in NY).
Yes, they could have kept Ghost, first they'd have to fire AV and eat $15M, then they'd have to live with a hole on defense, b/c Ghost was meh in Zona (he actually was valued less by the league than Braun last TDL!). Which was fine if they committed to a rebuild after 2020-21.
So in the end, it comes back to the FO.