I'm a Hextall fan (I think that most goalies are
), so I'm a bit biased. He was relatively above average right up to the bitter end (his last season was dreadful).
One interesting thing:
https://www.hockeygoalies.org/bio/hextall.html
His variance in 1992-93 was a 1.15, which is significantly above average, and also the highest of his career (by far). If you look at his game-by-game records, that's evident as well (you see some spectacular performances countered by some dreadful nights). In the playoffs against Montreal, he matched Roy very well in the first four games, but fell off of the cliff in Game Five (five goals on 29 shots) and Game Six (five goals on 23 shots).
He also played the easiest schedule of his career (other than his last season) with an average opponent 0.15 goals below average. His schedule wasn't much easier than Fiset (-0.07) or Cloutier (-0.39), though.
Having said that, I don't remember the details with 100% clarity, but I believe that the trade to the Islanders was more a result of expansion draft machinations than anything else. (Other than draft picks), Mark Fitzpatrick was the return, and he was a Florida Panther four days later.