The beginning of the season has brought disappointment for many teams who were hopeful they’d start the season better than they have. However, for some, it has also brought optimism. With playoff implications looming, there are a handful of teams entering Week 4 with an undefeated 3-0 record. Are these undefeated teams legit?

Arizona Cardinals

The Cardinals are 3-0 for the first time since 2015 on the heels of the dynamically spectacular play of Kyler Murray. They have talented playmakers everywhere on offense with DeAndre Hopkins and A.J. Green, who’s enjoying somewhat of a renaissance to his career. Averaging 34 points keeps them in every game. However, the Cardinals will only go as far as their defense takes them.

Furthermore, in all honesty, they haven’t played anyone of significance yet. Two of their three wins could have gone either way. There was a one-point win over the Minnesota Vikings when Minnesota’s kicker missed a chip shot to win the game and the Jacksonville Jaguars were leading late before Arizona pulled away to seal the game. Ultimately, as previously mentioned, this team will go as far as their defense will take them.

Las Vegas Raiders

This had to have been what owner Mark Davis envisioned when he paid Jon Gruden a $100 million salary and moved the team to Las Vegas. The Raiders, who flirted with many other free-agent quarterbacks during Gruden's tenure, currently have the best offense in the NFL. Beating the Baltimore Ravens in Week 1 gave that team momentum for the next two games in which they subsequently beat the Pittsburgh Steelers and the Miami Dolphins—all three of those teams won double-digit games last season.

However, similarly to the Cardinals, this team will go as far as their defense takes them. They cannot stop the run and I don’t know that Derek Carr can keep this record-breaking pace up to carry this team in December. For me, there are still questions about this team that need to be answered.

Carolina Panthers

Speaking of quarterback resurgence, how about the way Sam Darnold is playing for the Panthers? His stellar play (along with their defense) has helped Carolina start the season by beating the New York Jets, New Orleans Saints, and Houston Texans. In all fairness, neither of those three teams are projected to make any significant noise in December, aside from maybe New Orleans being a potential dark horse.

However, the Panthers are built to last based on how the roster is constructed. They have one of the best defensive fronts in the NFL. Let's hope that injuries to Christian Mccaffrey and Jaycee Horn don’t put more pressure on Darnold and he reverts back to the player he was in New York.

Denver Broncos

The Broncos have one of the most talented rosters in the NFL from top to bottom. I've expressed many times that I felt they were simply steady play from the quarterback position away from challenging for a wild-card playoff berth. Well, Teddy Bridgewater has brought that to their offense. Not to mention that, defensively, Von Miller has come out and played like a player with a lot to prove this season—and rightfully so.

Head coach Vic Fangio is one of the most stellar defensive minds in the history of the NFL and they've got talented players on defense. Injuries to Jerry Jeudy and KJ Hamler are causes for concern along with the fact they've only beaten the New York Giants, Jacksonville Jaguars, and New York Jets. However, their ability to play good defense and run the football has them set up to make a potential late-season run.

Los Angeles Rams

The Rams are looking like the best team in the most competitive conference in the NFL. They already had defensive superstars Aaron Donald and Jalen Ramsey. However, the addition of Matthew Stafford and DeSean Jackson has brought an even more exciting element to their offense and has made their offense must-see TV. All three of their wins thus far have come against teams that made the playoffs last season (Chicago Bears, Indianapolis Colts, and Tampa Bay Buccaneers).

Furthermore, in a statement game against the defending Super Bowl champions, they completely outclassed Tampa Bay. Sean McVay schemed circles around Todd Bowles’ defense. Overall, considering that the Rams play in the NFC West and stomped a mudhole in the Buccaneers, it is likely that the Rams are entrenched as a top-three NFL team.