DENVER — In his routine postgame press conference, Denver Broncos’ head coach Vance Joseph was about as even-keeled and monotoned as it gets. While it wasn’t on the Bill Belichick level of “check the guys pulse to see if he’s alive” mumble, his “so that’s a good thing” response—when talking about how the team didn’t have any injuries—sounded about as excited as a kid receiving coal on Christmas morning.

“Definitely pleased to be 3-1,” Joseph said with a smidgen more excitement after his team’s 16-10 victory over division rival Oakland Raiders. “That was huge for us today.”

The reason for Joseph holding back his excitement following what he called a “huge” win? He believes his team, although 3-1 through the first quarter of the season, can be significantly better than it has been through the first month of the season.

“What I like about our football team right now is our run defense has been excellent,” he said again with little joy coming from his vocal cords. “Running the football with our offensive line and our backs has been excellent.”

But with the exception of winning the Super Bowl there is always a “but” following praise by a head coach in the National Football League. On Sunday, the “buts” were few, but select. In Joseph’s mind, the game shouldn’t have been a six-point game, it should have been a blowout.

“The defense played very well outside of probably two big plays,” Joseph said. “We were great on third down. They were 2-for-15 on third downs. We had eight three-and-outs today. The start of the second half they were minus three, minus eight, minus 19 yards on the drive, and minus one. Definitely, we played really stout today outside of the two big plays and the one obviously for a touchdown. We can’t do that. Very pleased with the defense.”

On the defensive side of the ball, the Broncos were nearly flawless—holding the Raiders without a first down on eight of their twelve possessions. On 53 offensive plays, the Raiders were held to 10 points and 254 yards—both very respectable figures against an explosive offense. But it would have been much different if it weren’t for a few slip-ups.

“Defensively, we gave up two big plays today in the pass game with the same play from the Chargers game. It’s an identical play,” Joseph recalled going back to the team’s 24-21 win over the Los Angeles Chargers in Week 1. “We have to fix those things moving forward.”

Two big plays can cost a team a game, and even a season. On Sunday, the Broncos gave up a 67-yard touchdown through the air as well as 28, 22 and 20 yard passes. On these four plays, Denver gave up 137 yards to the Raiders. The other 49 plays they gave up 117 total yards.

Through the first four games of the season, Denver’s defense has given up a franchise-best 203 rushing yards, holding the starting running backs of each team to a combined 1.9 yards per carry.

“With a [running] back like that and an offensive line like that, that’s really special, 24 yards,” Joseph said after the Broncos held Marshawn Lynch and the Raiders to a season-low in yards on the ground. “Our run defense has been stout the entire year.”

On the other side of the ball, Joseph’s frustration came in the same manner—a few missed opportunities kept the offense from realizing its full potential.

“My issue with our football team right now—we make a lot of critical errors. That has to stop. Offensively, we’re 0-for-4 in the red zone with one false start,” the head coach said sternly as if his team had been blown out. “It’s really self-inflicted wounds. It’s a false start and there’s a holding penalty, we can’t do that. We’ve got to score points [in the red zone] and we had a missed field goal. That part of our offense we have to fix quickly.”

Going 0-fer in the red zone will lose games, much like giving up a few big plays on defense will lose games. But the fact that the offense had four red zone opportunities shows they are continuously putting themselves in an opportunity to succeed.

“I just felt like we were always one play away from really getting momentum. We just didn’t really have rhythm, and they did a good job mixing up coverages, defenses and safety pressures,” Broncos’ quarterback Trevor Siemian said on the offenses drives stalling. “I think we’re hurting ourselves [in the red zone]. I’ve got to watch everything, but we have to find a way to get touchdowns instead of field goals. I thought the first week we did a good job of that. We’ll figure it out, clean it up on the bye and be ready to go.”

In Week 1 against the Chargers and Week 2 against the Dallas Cowboys, the Broncos’ offense went a combined 7-for-9 in the red zone, scoring an average of 33 points. In Week 3 against the Bills and Sunday against the Raiders, however, Denver went a combined 1-for-7 in the red zone, only putting up 16 points in each game.

“We just have to make plays, us as playmakers [have to] make plays,” Denver’s running back C.J. Anderson said postgame. “I can call one for me particularly if I catch the ball clean, who knows what happens.”

Much like a parent giving their child the “I’m disappointed in your talk,” Joseph’s tough evaluation on his team is because he believes this group can be special.

“We had a couple plays out there that we need to clean up,” Broncos’ 325-pound defensive tackle Domata Peko Sr. said with a much more joyful tone in his voice than his head coach. “We’re going to make a run and we’re just going to keep getting better.”

The reason for positivity? The team is 3-1, undefeated at home and at worst, tied for second in the entire AFC after the first quarter of the season.

Even with “crucial” mistakes that can be counted on one hand on each side of the ball, the Broncos pulled out the victory. If they don’t fix these issues, it appears they’ll still be competitive. However, if these mistakes straighten out, the outcome may just bring a different, more joyful, tone to Joseph’s voice.

“I’m excited about what we can do,” Siemian concluded while only showing the faintest of grins.