It's not the middle of the regular season. But the bye week comes at the middle of the long stretch of work for Bills players and coaches. They went to training camp in Rochester 11 weeks ago. And they've got 11 weeks left in the regular season. For them, it's the midway point in a marathon of practices, meetings and games. For them, the bye week is situated in the perfect spot.

It also gives us a chance to assess where the team is with four wins in the first five games. Here's a list of some of the top things we've discovered about the 2019 Buffalo Bills so far this season:

THE DEFENSE IS SPECTACULAR

It was good last year; the Buffalo defense finished second in the league in 2018 in yards allowed per game. Now, it's great. The Bills defense is third in the league, and in the top 10 in virtually every important defensive category. And now they're not giving up points.

Through five games, the Bills are allowing just 14 points per game this year; only the Patriots and the Bears give up fewer points. Last year, the solid Bills defense gave up 23.4 points per game.

During the offseason, Bills defenders talked about red zone defense as their number one target for improvement in 2019. Last season, the Bills gave up touchdowns 71 percent of the time their opponents entered the red zone. They're better now, allowing TDs 60 percent of the time. But there's still room for improvement there.

They're getting takeaways on defense at virtually the same rate as last year; 1.6 takeaways per game. And with five sacks at Tennessee last Sunday, the Bills have moved near the middle of the pack in the NFL in sack percentage. 

Year three in Leslie Frazier's defense is shaping up to the best year of his tenure in Buffalo.

MENTAL TOUGHNESS ON DISPLAY IN ROAD WINS

The Bills have started out 3-0 on the road this year – the first time they've won their first three road games since 1993 (a Super Bowl year). Last season the Bills finished the year with two wins on the road.

In each of their road wins this year, the Bills have needed fourth quarter touchdowns to clinch it. They came from 16 points down in the opener at the Jets and won the game. That's indicative of a tough-minded, resilient team that can bounce back from deficits away from home.

"I know this about our team, that they're mentally tough," Sean McDermott said this week.

"I've said this for a couple weeks now they're a physically tough group and to win games the way we've won them and that's kind of the nature of the NFL, too, very few blowouts. And so, you've got to be able to play well down the stretch in the fourth quarter. And I think we've shown that we can do that," he added.

NEW ROSTER ADDITIONS PLAYING IMPORTANT ROLES

It doesn't take much to see how critical it was for the Bills to dive into the offseason free agent pool and sign some important players, especially on offense.

Wide Receivers John Brown and Cole Beasley are the top two pass catchers on the team. Running Back Frank Gore is Buffalo's top rusher, with two touchdowns and an average of 4.4 yards per carry. Mitch Morse has started every game at center and Lee Smith has started four of five at tight end. Quinton Spain and Jon Feliciano haven't missed a start yet at left and right guard, respectively, and Feliciano moved inside to play center when Morse got hurt last Sunday.

Throw in contributions by wide receivers Andre Roberts and Duke Williams, and it's clear the Bills made strong additions via free agency last spring.

DEPTH MAKES A DIFFERENCE

The first five games of the Bills season have not been without challenges. They've battled through injuries, losing Roberts, running back Devin Singletary, tight end Tyler Kroft, defensive tackle Harrison Phillips, cornerback Taron Johnson, and others for portions of the season.

But they have found answers. Siran Neal has led a platoon of replacements at the nickel corner spot in place of Johnson, a group that includes Dean Marlowe and Kevin Johnson. When Harrison Phillips went on IR, Jordan Phillips' role in the defensive line rotation increased and he wound up with a spectacular-career best performance with three sacks at Tennessee. Duke Williams made a splash in his NFL debut last Sunday, and Spencer Long and rookie Ryan Bates came off the bench for snaps on the offensive line.

Coach Sean McDermott says the offseason scouting work performed by general manager Brandon Beane and his staff is paying off when it comes to depth on the roster.

"A lot of credit goes to Brandon on that and his staff," McDermott said this week. "And then the mental toughness of our football team and the preparation of our football team, not just the starters but the other guys that came in and stepped in and stepped up. Without those guys, we may not win that football game (Titans)."

BILLS ROSTER MAYBE NOT A FINISHED PRODUCT

Even with an active offseason and the addition of depth, Brandon Beane may not be finished with his Bills roster. He traded away wide receiver Zay Jones this week for a 2021 draft pick and re-signed running back Senorise Perry, who may have a role to play on special teams.

There's three weeks until the NFL Trade Deadline. Based on his track record through two and a half years, Beane may have more roster adjustments in mind down the stretch.

JOSH ALLEN MAKING PROGRESS, BUT MORE TO COME

His 53 percent completion rate last year is up to 63 percent now. His QB rating of 67.9 last year is at 75.2 this year.

But the numbers only tell part of the story of quarterback Josh Allen's start to the 2019 campaign. He said he played a "complete" game Sunday in Tennessee and he's right. He bounced back from a rought performance against New England in Week 4.

Allen is working on protecting the ball and throwing fewer interceptions and accepting the short and intermediate range targets he's been provided through the air. He's on a definite upward curve, with more progress likely to come as the season moves along.

HOME FIELD OPPORTUNITY AWAITS

After playing three of their first five on the road, the Bills are looking at three straight home games after the bye. Two of them are against opponents who haven't won a game yet (Miami and Washington).

The schedule toughens up around Thanksgiving so clearly this is the time for the Bills to stack up wins for a playoff push.

UPDATE ON "THE PROCESS"

If you've "trusted the process" all along-congratulations. It's working now. If you were skeptical about "the process," don't worry-there's still time to climb aboard.

Even with two thirds of the schedule still to be played, national observers are already lavishing praise on Sean McDermott and Brandon Beane for their long-term vision for the Bills.

But McDermott isn't buying it.

"Our focus really is on what happens inside these walls and just focusing on one week at a time continuing to grow as a football team," he said this week. "So, that's all we can control. We're 4-1 and a whisker away from being 5-0, but the fact is we're 4-1 and with a lot of room for growth."

"A lot of good progress to this point in the season and a lot of good football that we've played. So, I give credit to the players and the staff. We've got to continue to work and grow as we move forward."

Sounds like a plan.