Well, Tavares has some weird playoff numbers, 22 points in 24 games.
But 67.7% O-zone starts, and 10 block shots in 24 games.
It's almost like he's a one dimensional scorer.
Actually he hasn't played bad in the playoffs
1.90 PP/60, CF 52.88, CFrel, +5.81, xGF 53.14, xGFrel +6.43
And blaming him for the Islanders not winning? That's a stretch.
On the other hand, you can also make the case that the goalies, not JT, were the key to success:
2013-14, 79 points,
2014-15, 101 points, 2.99 gpg, Halak 38-17-4 .914, other goalies 9-11-3 .888
2015-16, 100 points, 2.77 gpg, Greiss/Halak 41-24-8 .922, other goalies 4-3-2 .904
2016-17, 94 points, 2.91 gpg, Greiss/Halak 38-27-10 .914, other goalies 3-2-2 .889
2017-18, 80 points, 3.18 gpg, Halak/Greiss 33-34-8 .902, other goalies 2-3-2 .908
Note: outscored opponents by 20 goals, but wide open game killed them
2018-19, 106 rate, 2.82 gpg, Greiss/Lehner 34-17-6 .929
So the major difference was Weight, team is basically playing the way they did before Weight, with Barzal replacing JT.