Derrick Hall satisfied with D-backs’ buying and selling Grace expects Greinke trade to have emotional impact Top Stories The Cardinals hope that’s enough to help Palmer build on his success … and to keep him healthy. Carson Palmer may not be the best quarterback in the NFL, nor the most skilled.He’s not the most durable, and to the Arizona Cardinals, that point is most painful. But after acknowledging that, there is a very valid argument to say Palmer is the league’s most indispensable quarterback.MMQB’s Peter King backs that argument.In his column Wednesday, King took a look at a few of the NFL’s best quarterbacks and compared their teams’ records when they are healthy and when they were out of action. The 5: Takeaways from the Coyotes’ introduction of Alex Meruelo Unlike most teams that go deep out of running formations with extra blockers, Arizona is especially likely to go deep off empty sets — that’s a spread formation without a running back in the backfield. Leaving the quarterback susceptible in an empty set is risky enough, but overcoming the lack of blockers can be done with a quarterback who knows what defense he’s looking at and where his receivers will be, Benoit writes.Palmer is the reason the Cardinals can flourish in empty sets. It’s not that he’s a superstar quarterback (those days are past), it’s that he’s a very professional one. He’s tough and fundamentally sound in the pocket. He’s smart and works smoothly from one progression to the next. Progression reads are the nexus of Arians’ system—Arians calls it a “scratch where it itches” system, meaning it’s not tethered to any one player. Instead, it’s tailored to exploiting a defense’s specific weaknesses via aerial concepts. It’s clear that general manager Steve Keim attacked the offseason hoping to build around this idea.He signed Mike Iupati (who is out to start the season with a knee injury) to strengthen the offensive line. He drafted receiver J.J. Nelson to play next to the equally speedy John Brown, which should give Palmer the opportunity to get rid of a deep throw sooner — as in, before he’s hit by a blitz. Comments Share Former Cardinals kicker Phil Dawson retires By record, it’d be easy to say the Cardinals suffer more than a number of teams — the Packers without Aaron Rodgers, the Patriots without Tom Brady — when their starter is out. The Cardinals are 13-2 when Palmer starts and 5-6 when he doesn’t since the midpoint of 2013 — that includes a 2-6 record once the quarterback when down after tearing his ACL last year.Writes King:It’s possible Palmer is the most indispensable quarterback on a playoff contender in the league. I always wonder what that kind of pressure—from a locker room, from a coaching staff, from an organization, from a community, from a state—feels like for a quarterback. Boomer Esiason once said that he loved that for three hours a week in the fall, he controlled how a region felt. He just loved the power.And the less bombastic Palmer?“I actually love that,” Palmer said while Arizona’s locker room cleared out after the Aug. 22 game against San Diego. Scheme-wise, evidence to answer why the Cardinals suffer without Palmer can be found in another MMQB piece, this one by Andy Benoit.Head coach Bruce Arians is well-known for his aggressive, down-field attack, and it’s clear that relies quite a bit on Palmer taking the snaps.