Are the Cardinals the best team in the NFL after Zach Ertz's addition?

On Friday, the undefeated Arizona Cardinals got even better after they acquired tight end Zach Ertz from the Philadelphia Eagles. In exchange for Ertz, the Cardinals dealt a 5th-round pick and rookie cornerback Tay Gowan to the Eagles.

Arizona pulled the trigger on the trade after losing tight end Maxx Williams for the remainder of the season due to an injury he suffered in Week 5 against the San Francisco 49ers.

Losing Williams for the season is a blow, but the Cardinals may have gotten even better than they were before this trade.

Are the Cardinals the best team in the NFL?

There's a lot to like about the Cardinals' current roster. Kyler Murray is currently an MVP candidate and with superstars like DeAndre Hopkins and A.J. Green, the offense has been playing lights out under Kliff Kingsbury's Air Raid system. The passing defense is stopping everybody who tries to beat the Cardinals through the air.

San Francisco 49ers v Arizona Cardinals

The only area where the Cardinals lack quality is their run defense. Even with Jones and Watt in the front seven, the Cardinals allow 5.4 yards per carry on average, which is the second-highest mark in the NFL, just below the Los Angeles Chargers' 5.6.

Sure, it's great to have a strong pass defense in a division that boasts Matthew Stafford and Russell Wilson. However, teams such as the San Francisco 49ers and the Los Angeles Rams are also great at scheming to run the football effectively, and this could become a big problem in the latter stages of the season.

The Cardinals are a fantastic team. They'll likely reach the playoffs as the #1 seed in the NFC unless tragedy sticks. But they aren't as good as the AFC's Buffalo Bills, who have no noticeable holes on their roster.

Will the Cardinals remain undefeated through the regular season?

Arizona's undefeated record likely won't survive until the end of the regular season.

The Cardinals will play the Cleveland Browns on Sunday, and if the Cardinals can't defend the run, they'll suffer. The Browns average 5.4 yards per carry, which is the highest in the league, so expect Cleveland to have a lot of success against Arizona's run defense.

Last year, the Pittsburgh Steelers started the season with an 11-0 record, but finished 12-4 and lost in the first round of the playoffs. The Tampa Bay Buccaneers lost their season opener but went on to win the Super Bowl.

Being the best team in the NFL in September or October doesn't matter. What matters is being the best team in the league in January.