One of the most stressful jobs in the NFL is the salary cap
manager. He or she doesn’t get an untethered vacation, they are
consistently clawed at by players and agents for more of the
salary pie, and have to please a GM, a head coach and of course,
their owner(s). In doing so, they are constantly negotiating
year round to keep, acquire and cut salaries of players.  When
you do business long enough in the NFL, you get a good idea of
how these cap managers operate. Including their strengths, their
weaknesses and their tactics. Conversely, they also get a feel
for the style and strategy of the multiple agents that they must
deal with.   The used car salesman can't always get the deal
done.  The Car Salesman: This cap manager has little authority
to do a deal. He/she has to run back to the GM, or the HC or the
owner on every move he/she makes. Just like a car salesman when
he says they have to talk to the manager to authorize a deal.
Ultimately, they are a mouthpiece in which a higher authority
hides behind. The