The Arizona Cardinals were the worst team in the NFL in 2018. They were awarded the first pick in the 2019 NFL Draft. With that pick, they selected quarterback Kyler Murray — and so the rebuild begins.

Through the rest of the draft, the Cardinals continued to take players that can help immediately and can also turn into superstars down the line.

With that in mind, 2019 should be an interesting year for Arizona. You'll see a lot of young talent on the field as the Cardinals try to find an identity. Perhaps they will surprise us all and make a playoff push, or they could struggle in Year 1 of a new era and get another top draft pick in 2020.

Whatever the case, a few players could define their season. Here are the three main X-factors for the Arizona Cardinals in 2019.

Kyler Murray

Kyler Murray, Cardinals

The first overall pick in the draft is a quarterback (arguably the most important position in the game). If you needed any further proof that Murray would be on the list, note that Kyler Murray was the only player name-dropped to start the article. That's A+ foreshadowing.

Murray is obviously going to be an X-factor for the Arizona Cardinals this year. The play of the quarterback will weigh more on the team than the play of any other player. Murray, as the first overall pick, has this weighing on him more than most.

Murray is an X-factor for 2019 no matter what. Yes, how the Cardinals play in 2019 matters. Obviously the team will try to make positive steps. That being said, even if the Cardinals struggle, Murray's overall play could keep the franchise happy. His play is the X-factor of the entire season, considering he could keep them positive about the future even if 2019 doesn't end well.

David Johnson

David Johnson, Cardinals

Murray will need some pressure taken off him. One of the best candidates to do that is David Johnson. The running back was considered to be near the top of the mountain not long ago. It's not a stretch to say a lot of people believed him to be the best at his position.

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However, an injury in 2017 limited him to just one game. While he appeared in all 16 games last year, he wasn't the same player. His yards per carry were down to 3.6 and he didn't even touch 1,000 rushing yards. Johnson's receiving numbers were down drastically as well.

Now the running back is far removed from that injury. He has had even more time to heal and there are now more weapons around him that should protect him.

The question is, will he return to 2016 David Johnson? If that happens, the Cardinals are back in business. Johnson will take loads of pressure off Murray and the development of the offense could be fast-tracked.

David Amerson

david amerson

Patrick Peterson is suspended to start the year. The best cornerback in the NFL isn't available to the Arizona Cardinals for the first six weeks of the season.

With that in mind, the Cardinals are going to desperately need someone to step up in their secondary – specifically at cornerback.

The defense has a lot of solid pieces that should make the unit formidable. However, that could be negated in the early weeks if no one on the secondary can step up. That's where David Amerson comes into play.

Amerson showed a lot of promise in the first two years of his NFL career (back with the Washington Redskins). With the Oakland Raiders, he kicked it up a notch. Amerson was fantastic in 2015 and 2016, but took a slight step back in 2017.

In 2018 (his first year in Arizona), Amerson reverted to someone who has loads of potential, but looks lost at times.

If Amerson can be that top-tier cornerback he has proven he can be, the Cardinals won't be crippled too much by the loss of Peterson.

David Amerson can keep them afloat while Peterson is gone; therefore he's one of the most important players on the roster who could be a major X-factor in 2019.