Celtics' Complete 2021 NBA Offseason Guide

Early submission for the theme of the Boston Celtics' 2021 offseason: Expect the unexpected.

Some degree of change felt likely after the Shamrocks were bounced from the opening round in five games by the Brooklyn Nets. But props to anyone who had former president Danny Ainge retiring and former coach Brad Stevens replacing him on their Bingo card.

With an early shuffle like that, there's almost no telling what kind of NBA news the Celtics will generate in the coming months.

It's a good time, then, to look ahead at what awaits the organization over this offseason.

The Celtics could theoretically have an otherwise quiet offseason.

Eleven different players have guaranteed contracts for next season. That includes Jayson Tatum, Kemba Walker and Jaylen Brown, who will each collect more than $25 million.

The group also has the expiring salaries of Marcus Smart ($14.3 million) and Tristan Thompson ($9.7 million). If Boston makes a major trade this summer, one or both players seems likely to be involved to help make the money work.

Jabari Parker's $2.3 million salary is non-guaranteed, though he gave the Celtics something to think about after arriving in April. The second overall pick in 2014, he had Boston's seventh-highest scoring average in the postseason, averaging 8.5 points in 14.8 minutes per game on 61.9 percent shooting.

Absent from the group is spark plug swingman Evan Fournier, who was Boston's biggest trade deadline addition. He is headed for unrestricted free agency, though the fact the Celtics traded for him ahead of time seemingly indicates a desire to keep him around.

Boston has both of its picks in the upcoming draft. Those landed at Nos. 16 and 45.

Beyond selecting a new head coach, Stevens has two major decisions to make with this roster.

The first is what to do with Walker. He has been an All-Star in the past, which gives him name recognition and a matching salary ($36 million next season with a $37.7 million player option for 2022-23). But he's in the middle of a year-plus fight with his bothersome left knee, which limited him to 43 games this past season and neither of Boston's final two playoff tilts.

It's easy to see the Celtics should search out trades, but finding a trade partner is tricky. The Athletic's Jared Weiss reported Walker is seen "as having negative trade value," so it might cost Boston an asset or two just to get rid of Walker. In that case, maybe it's best to just keep him around.

The other is Fournier's free agency.

The Celtics need his blend of complementary scoring, shooting and distributing, but he won't be cheap. With the organization already hovering near the tax line, the cost for keeping Fournier could be multiplied by the tax.

"If the Celtics signed Fournier to a conservative contract starting at $10 million, there would be an additional $19 million counted toward the luxury tax," ESPN's Bobby Marks relayed. "That means Fournier would cost $29 million for one season."

Boston's buying budget mostly hinges on how aggressive it will be in trades.

If the Celtics are ready to move on from Walker, they're probably looking at other players with imperfect situations and massive salaries. Kristaps Porzingis could be an option after a dismal playoffs with the Dallas Mavericks. Al Horford might be another if the Oklahoma City Thunder see Walker as a better fit for their young roster.

Marcus Smart should have more trade value in a vacuum, but his offensive shortcomings and mid-tier salary might limit the potential return. The Celtics might try enticing a team that needs to balance their roster with more defense, perhaps someone like the Sacramento Kings in an exchange built around Buddy Hield.

On the free-agent front, Boston will be bargain shopping for bench scoring, perimeter defense and floor-spacing in the frontcourt. The list of possible targets include Doug McDermott, Otto Porter Jr., Paul Millsap, JaMychal Green, Rudy Gay and Patty Mills.

All stats courtesy of NBA.com and Basketball Reference unless otherwise noted.

Zach Buckley covers the NBA for Bleacher Report. Follow him on Twitter, @ZachBuckleyNBA.