QB Kyler Murray aside, Isaiah Simmons is the most important player on the 2020 Arizona Cardinals

The 2020 Arizona Cardinals are all about Kyler Murray's development, as head coach Kliff Kingsbury is poised to help him with the infamous second-year breakout that generally exists when it comes to top-drafted quarterbacks.

Of course, a lot of things have to go right for that breakout to reach the magnitude we observed from the likes of Carson Wentz, Patrick Mahomes and Lamar Jackson. And among those things is the chemistry with new teammate DeAndre Hopkins, so one could make the point that Hopkins is — Kyler Murray aside, of course — the most important player when it comes to the Cardinals' success this year.

[Editor's Note: PFF's advanced statistics and player grades are powered by AWS machine learning capabilities.]

While I would be crazy to suggest that anyone else but Murray is the clear-cut most important player to Arizona's success in 2020, I'll go another route for the second-most-important player and make the point for a rookie.

Concretely, I think No. 8 overall draft pick Isaiah Simmons — a positionless defensive weapon — is the key to a much-needed defensive turnaround in Arizona. It's a role that makes him the team's most important player behind their second-year quarterback.

In terms of PFF grade, the Arizona Cardinals had an above-average pass-rush in 2019 and generated pressure at an above-average rate. However, they still had the second-worst pass defense in terms of expected points added (EPA) allowed per pass play, with only the Raiders being worse.

Granted, this might be driven by volatile and high-value plays like interceptions (nobody came away with fewer picks than the Cardinals in 2019). But it also doesn't look any better if we measure consistency, as the Cardinals' pass defense ranked dead last in the rate at which they gave up successful plays (plays with positive expected points added).

So, as the pass rush was apparently not at fault, the problem was, of course, the coverage unit, which finished the season with a 41.8 unit grade, the second-worst in the NFL.

The Cardinals had a problem over the middle of the field