PKJIM rues: The difference is that in most NFL games, the players play hard for 60 minutes knowing that every play counts. NBA players play 75% for 3+ quarters and 90% for the last 5 minutes.
SH: I've talked to a couple guys with NBA experience and they assure me this is baloney.
Sure, not every player can give that 90-100% focus and exertion for a full 40+ minutes every single nite.
But with few exceptions, they all try. Those that don't try that hard (for example giving just "75%" first 3 1/2 quarters) will eventually be beaten out of a job by a guy who will give 80, 85, 90% or more.
Remember that for the top 100 players, a full time, full salaried job might well be a "sure thing" provided they show up and give a consistent winning effort more nights than not.
But that leaves another 200-250 players who are working their asses off to make it into the top 6-7 rotatation, or to qualify for a bigger or longer term contract.