Hughes is really skilled, but really small - some of these guys thrive (Gaudreau) others get dinged a lot.
And McJesus couldn't carry Edmonton, Crosby even with Malkin couldn't carry the Pens past the first round for a stretch.
The difference between Hughes and Patrick, Frost) might be 40 points or 15 goals (0.37 goals per point, assuming he reaches his full potential and is in the same class as Crosby and McJesus, which is not a given). That's good, but not enough to put a team over the top.
Nor can you assume Hughes will immediately produce:
Matthews, 69, 63 his first two years
McDavid, 48, 100, 108
McKinnon 62, 38, 52, 53
Nugent-Hopkins 52, 24, 56, 56
Hall 42, 53, 50, 80 / Seguin 22, 67, 54 (PR), 84, 77
JT, 54, 67, 81
Stamkos 46, 91, 95
Kane 72, 70, 88, 73
Crosby 102, 120
Point is Flyers have good players, are adding more, and if they just end up with a 40 point ES forward instead of Hughes, it's not going to make or break them. Hart is more valuable to the Flyers (if he becomes an elite goaltender) than Hughes could ever be. The difference between a .910 and .920 S% is about 26 goals a year (2600 save attempts is the league average, every 0.005 is worth 13 goals).
The progress of the prospects already in the system as a group is far more important to the Flyers' future than where they end up in this year's lottery.