Is the Boston Celtics' next star already on the roster?

That missing piece for the Celtics might not be missing after all, with Marcus Smart pegged as a future All-Star by CARMELO player projections. Bob DeChiara/USA TODAY Sports

While Boston Celtics fans obsess over trade speculation with hopes that a midsummer blockbuster might deliver another established star and cement the team's status as a legitimate contender, here's something to ponder:

What if the next star is already on the roster?

Even after the signing of free-agent big man Al Horford this summer and an upgrade of a team that won 48 games last season, there's a lingering belief that Boston must add at least one more impact player to truly compete with the Cleveland Cavaliers, the clear front-runner in an otherwise jumbled Eastern Conference.

Many in an impatient fan base are willing to splurge on established talent and part with the sort of assets that could strip Boston of exactly what has positioned the team to rejoin the upper crust.

We've repeatedly suggested in this space that patience might be Boston's best path to a sustained run as a true title contender. Some are so obsessed with adding the clear No. 1 in a new Big Three -- a trio that would also include Horford and Isaiah Thomas -- that it's easy to overlook the fact that the team might already have a third amigo in waiting (even if that person isn't a clear-cut No. 1 in such a trio).

FiveThirtyEight released updated CARMELO player projections last week, and it was hard not to notice the glitzy prediction for third-year guard Marcus Smart.

CARMELO didn't just predict a monster leap for Smart this season; it pegged him a "future All-Star" with a value of $156.5 million over the next five seasons. After Smart produced 2.5 Wins Above Replacement last season, CARMELO projects him to more than double that total this season (5.1) and suggests he'll make a pronounced offensive leap that will raise his on-court value to $26.2 million this season (he'll actually earn just $3.6 million on his rookie-scale deal).

To put Smart's CARMELO projection in perspective, Thomas owned a 7.3 WAR last season and is projected to drop to 4.9 this year. Jae Crowder, maybe Boston's closest thing to an All-Star behind Thomas last season, posted a 6.1 WAR last year and is projected to dip to 4.5. Of players currently on the Celtics' roster for the 2016-17 season, only newcomer Horford (8.9 WAR last season) is projected to have a higher WAR than Smart this year (Horford is projected at 5.7).

CARMELO projects Smart to have the fifth-biggest leap in WAR among all NBA players next year. He trails only Anthony Davis (plus-3.7), Kristaps Porzingis (plus-3.1), Kyrie Irving (plus-2.8), and Andrew Wiggins (plus-2.8).

CARMELO acknowledges a high volatility with Smart. At one extreme, he's a fringe rotation player with offensive struggles that make him a liability. At the other, however, it projects Smart with a WAR as high as plus-9.9 (or one win below the 10.9 WAR projection for the much-desired Kevin Durant). Regardless, even Smart's mean projection of 5.1 WAR is just south of summer rumor favorite Blake Griffin, who is projected at 5.9.

Of course, there is no guarantee that Smart will make this projected leap. There are obvious obstacles in his path, including Boston's guard depth, which should leave him operating in a reserve role behind incumbent starters Thomas and Avery Bradley. The departure of Evan Turner, however, should open a big minutes void that Smart can help fill off the bench.

Smart is in Las Vegas this week with USA Basketball, part of the Select Team that is training with the Rio-bound national team through Thursday. Being around that high level of talent, even for a brief stretch, should aid Smart's progress. For a Boston team that hasn't had much of a presence with Team USA over the past two decades, Smart could be Boston's best hope for a homegrown integration. (And, having competed for Team USA since winning gold with the under-18 squad in 2012, Smart has expressed a desire to be part of a future Olympic squad.)

Celtics fans will simply hope that Smart stays healthy heading into the season. Last year at summer league in Las Vegas, Smart dislocated two of his fingers while diving for a loose ball. Smart said being healthy for this entire summer would help him hit the ground running when the 2016-17 season arrives.

"I'm 100 percent healthy, and that's one thing I couldn't say the last two years, my first two years," Smart said. "I'm 100 percent healthy. With that being said, I'm working every day harder and harder, and getting better."

Pressed on what he's been working on this summer, Smart said, "My shooting. Everybody knows it. I know it. I've been working really hard on it. And my conditioning."

Smart shot just 34.8 percent overall last season and a meager 25.3 percent beyond the 3-point arc. He had a couple of hot streaks -- like one snow day-aided stretch in late January -- but never maintained his shooting. Injuries certainly didn't help his cause, but Smart is aware that he must improve his shooting to reach his full potential.

Smart averaged a manageable 27.3 minutes per game during the 2015-16 regular season, and with Bradley injured in the playoffs, his floor time spiked to 32.2 minutes per game in the postseason. While the Celtics will hope someone like summer standout Terry Rozier, a second-year point guard, can elevate to a rotation role, Smart will get every opportunity to be the sort of sixth-man force that Turner was last season.

Smart, the No. 6 pick in the 2014 draft, is already regarded as one of the better perimeter defenders in the league. He gives the team versatility by being able to guard bigger wings, and he pairs well with Bradley and Crowder to give Boston a defensive-minded trio on the perimeter. Adding Horford to the back line should only help a Boston team that ranked in the top 3 for defensive rating for much of last season.

Celtics co-owner Wyc Grousbeck noted in the aftermath of the team's pursuit of Durant that one of the free agent's biggest questions was if Celtics were committed to paying to keep their core together. As Grousbeck told Boston radio station 98.5 the Sports Hub, "Kevin asked, 'In two years, when all your young guys are coming up, are you willing to go way into the luxury tax to re-sign these guys and pay them whatever is necessary to keep them?' That’s what he thinks of our roster, by the way. 'Are you willing to go deep into the tax to keep these guys, like Marcus Smart-type guys?' We said absolutely."

The Celtics almost certainly will look to add parts to their roster before summer's end. Some might be disappointed if those moves are not as seismic as adding a player the caliber of Griffin or Russell Westbrook. Given that Boston can pursue those types of players next summer in free agency without giving up assets, all while assuring itself the ability to keep its young core intact, settling for quieter moves might be its best chance to be the sustained contender its fan base wants it to be.