The Boston Celtics are coming off of a thoroughly disappointing 2018-19 NBA campaign in which they won just 49 games and lost in the second round of the playoffs, about 10-15 wins and a couple of more playoff rounds short of expectations.

The Celtics' roster then experienced a mass exodus this offsesaon, as Kyrie Irving, Al Horford, Terry Rozier, Marcus Morris and Aron Baynes all departed, whether it was via free agency or trade.

Boston pivoted nicely, signing Kemba Walker and Enes Kanter, but the roster as a whole is questionable.

As a result, the C's are kind of a Wild Card team heading into the 2019-20 season, and it's going to take some big performances from the young guys in order for Boston to make serious noise.

So, here are three Celtics players poised for a breakout year (and no; Gordon Hayward doesn't count).

3. Robert Williams

With Boston losing both Horford and Baynes this summer, Robert Williams takes center stage as one of the Celtics' top big men, and that is both exciting and scary.

While Williams is incredibly talented and showed flashes of brilliance during his rookie year, he is still very raw, and it remains to be seen whether or not be is ready for regular minutes.

What you really have to love about Williams (other than his ridiculous athleticism) is his smarts. He knows where to be on the floor, and he isn't just a defensive wiz; he also has a strong basketball IQ on the offensive end.

Kanter will be the starting center, but given his defensive deficiencies, Williams will be expected to play a big role.

2. Jaylen Brown

The fact that Jaylen Brown is entering a contract year is probably enough in and of itself to expect a breakout season from the soon-to-be-23-year-old, but Brown really needs to start showing some consistency.

Brown had a nightmarish start to the 2018-19 campaign, and while he adapted in December and actually played pretty well the rest of the way, the stability just wasn't there.

We know how talented Brown is. He has All-Star potential, and he plays both ends of the floor. But there are holes in his game that need work, such as being more assertive in utilizing go-to moves and making his free throws.

With Irving, Horford, Rozier and Morris gone, Brown will certainly take on more responsibility, and it's up to him deliver over the entirety of the 82-game season, plus the playoffs.

1. Jayson Tatum

People expected a monster year from Jayson Tatum in 2018-19, but they didn't get it.

To be fair to Tatum, expectations were set a bit too high after his outstanding 2018 postseason. Those expecting him to bust out and average 20 points per game were kidding themselves. After all, the kid was just in his second season.

But now, with Tatum taking on the role of one of the team's clear-cut top options, the time has come for the 21-year-old to break out for good.

A big issue with Tatum last season was that he settled a bit too much, failing to take advantage of his physical gifts and instead relying too heavily on his mid-range jumper.

This year, however, Tatum needs to be more assertive, and he needs to be more efficient.

He doesn't need to average 20 a game, but it would be nice to see him bump his average up to around 18 points per game on the type of efficiency he had during his rookie year.