The Boston Celtics are coming off an incredibly disappointing 2018-19 NBA campaign in which they won just 49 games and were eliminated in the second round of the playoffs in a year where many thought they would make it to the NBA Finals.

But now, the Celtics have a new-look roster that seems to be looser, which might make all the difference in the world heading into this coming season.

Of course, Boston's ceiling is not nearly as high as it appeared to be going into last year. The Celtics have considerably less overall talent, and their depth has taken a hit.

Still, Boston widely regarded as one of the top teams in the Eastern Conference going into the 2019-20 NBA season.

Here are the four biggest storylines surrounding the squad as they get set to begin a new season.

4. Kemba Walker replacing Kyrie Irving

From a talent perspective, this is almost a wash. Kemba Walker isn't a huge dropoff from Kyrie Irving, and it is actually hard to find two point guards who are more similar in style.

But as far as the locker room dynamics? This is pretty significant.

Irving played a featuring role in destroying the Celtics' locker room this past season, and while he was not solely at fault, he was the driving force behind the meltdown.

Walker, on the other hand, is a terrific teammate and was beloved during his time with the Charlotte Hornets. Walker is already getting praise from some of his new Celtics teammates during their time together on Team USA.

Perhaps all Boston needed was a good veteran leader who isn't going to throw anyone under the bus, and Walker should provide that.

3. Jaylen Brown's contract year

Jaylen Brown didn't show much — if any — progress this past year, as he got off to an incredibly rough start over the first month and a half. He rebounded and had a solid season the rest of the way, but it wasn't the jump most expected.

But now, it's put up or shut up time for Brown, as he is entering a contract year.

With Irving and Al Horford gone, not to mention Marcus Morris, Terry Rozier and Aron Baynes, Brown's opportunity will almost surely increase, meaning a heck of a lot more touches for the young wing.

We know Brown is talented, but his consistency has been a rather big issue over the first three seasons of his career.

There are quite a few things Brown needs to work on (especially his free-throw shooting), so hopefully for his sake and Boston's, he has taken some strides this summer.

If he did, he could be in for a big payday next offseason.

2. Jayson Tatum potentially breaking out

Many were anticipating Jayson Tatum to take a huge step this past season, but while he was good, people were disappointed in his lack of progression.

The expectations placed upon Tatum heading into the 2018-19 campaign were definitely unfair given his age, but now that he is going into his third season, it's time for Tatum to bust out.

Irving certainly held Tatum back this past year, but now, he no longer has that excuse. Yes, Walker is now aboard, but he does not present some of the problems Irving did.

Tatum will almost surely become a focal point of the Celtics' offense this year, as Boston lost a whole lot of points and shots this offseason, whether it was Irving, Horford, Morris or Rozier.

Personally, I think Tatum will have a very big season and will begin stamping his name among the most exciting players in the NBA.

1. Gordon Hayward's Health

The 2018-19 season was not exactly smooth sailing for Gordon Hayward, as he labored through the first half of the year before finally beginning to gain his footing in February.

From February through Boston's first-round series against the Indiana Pacers, Hayward slowly but surely began to look like his old self, showing a burst we hadn't seen since his Utah Jazz days and looking very confident.

The Milwaukee Bucks series put an end to that, but in Hayward's defense, the entire Celtics team was miserable for those five games (well, aside from Game 1).

Now, Hayward has a full year of recovery from that gruesome leg injury under his belt, so he should certainly look a heck of a lot better this coming season.

Yes, Boston has Walker now, and all eyes are on the young guys, but Hayward's play is going to be the X-factor in determining whether the Celtics are a legitimate NBA Finals contender or a second-round exit waiting to happen.