The 2018-19 Boston Celtics will be remembered as one of the most disappointing teams in recent NBA history. Their inability to identify, unite, and extract as much production as possible from their five best players at the exact same time was, in many ways, a root cause for the overwhelming dysfunction that buried them.

Aware that Kyrie Irving and Al Horford were the team’s only night-to-night crunch-time locks, a grumpy game of musical chairs between Jaylen Brown, Marcus Morris, Gordon Hayward, Jayson Tatum, and Marcus Smart (Terry Rozier would also throw his own name onto this list if you asked him about it) ravaged Boston’s locker room and challenged the instincts of a respected albeit justifiably perplexed coaching staff.

This year, with Irving, Horford, and Morris gone, the Celtics head into training camp with less confusion about who their five best players are. But none — Kemba Walker, Smart, Hayward, Tatum, and Brown — stand taller than 6’8. To cram all on the court at one time feels like a voluntary kneecapping, but it may be necessary. Ten years ago this would be an unthinkable crisis. Five years ago, it’s worrisome. Today it’s more like an intriguing opportunity that begs some questioning: How often will these five actually play together, in what context, and can they twist their obvious debility into an unguardable strength?

Enes Kanter, Robert Williams, Daniel Theis, and even Grant Williams will provide some beef, rim protection, and a presence on the glass; at least one will be on the court a majority of the time. But none can subtly influence every possession like Horford, or do as Baynes did and transform into a sacrificial bag of bricks. With both gone, Boston’s most talented quintet of bigs is fragile where it used to be solid.

Ever since Brad Stevens became Boston’s head coach, defense has been the calling card. According to Cleaning the Glass, Stevens’ Celtics only finished one season with a defense that was worse than their offense (2017, when Isaiah Thomas spent the year as a lit match falling into a pool of gasoline). They’ve always respected the three-point line — with top-10 three-point frequency rankings in each of the past three seasons — but have not committed to a fast pace, or drawn enough shooting fouls. In six years under Stevens, the Celtics have had a top-10 offense in two of them, while the defense only dipped below league average during his rookie season. No teams were better in 2018.

This isn’t small ball for the sake of being one with the times, but a need to squeeze the most skill as they possibly can out of an uneven roster

However, it would be naive to believe this group will live or die on defensive stops. Instead, offensive potency has to be the barometer. Boston has little chance sizing up against the Philadelphia 76ers or Milwaukee Bucks, two conference favorites that were built to torment with overwhelming size, while the defending champions still have Marc Gasol and Pascal Siakam. But wills are tested every time a team swerves into the extreme. Who breaks first when Stevens goes extra small: Boston or its opponent?

This group also lets the Celtics slip beneath the underdog umbrella Stevens has historically thrived under. It’s a mentality they never grasped last year and will have no choice but to embrace going forward. Scrappy charm doesn’t always lead to success, but this particular group has just the right amount of talent and desperation to taste it.

The absence of a safety net (be it Horford or Irving) forces two-way focus on every possession. The margins are slim, but basketball teams are hard to humble when all five players are dialed in on the same gameplan, anticipating each other’s thoughts and actions. If this lineup gets there it can do things it shouldn’t be able to.

It’s symbiotic. Each member will be empowered but not dependent on another for assistance. Their worth will be appreciated and encouraged. This isn’t small ball for the sake of being one with the times, but a need to squeeze the most skill as they possibly can out of an uneven roster. Together, Smart, Brown, Tatum, Hayward, and Walker can be a fist. Defenses can’t trap or double-team any one of them; each one can punish mismatches, space the floor, and swim without the ball.

At the end of every close basketball game, each team should, in theory, have their five best players on the floor. There are instances where fit and awkward overlap seize control — if Stevens wants to go small without sacrificing defensive clout he can always turn to Semi Ojeyle — but we’re smack dab in the middle of an era that will partially be remembered as the dawn of positionless fluidity — an evolution that prioritizes talent consolidation.

The most successful proxies are from Golden State and Houston, where Draymond Green and PJ Tucker went up a position to leverage their girth, toughness, and intelligence. The Celtics don’t have a forward to fit this role, but they do have Smart, a 6’4 combo guard who would box a rhinoceros if his coach asked him to.

For eight or nine seconds at a time, Smart can slide onto just about anybody in the league and do battle. But he’s also three inches shorter than Green and weighs about 30 pounds less than PJ Tucker — another four who glues his team together when moonlighting as a five. Hayward is ripped. Brown is tenacious. Tatum is long. But this group’s defensive ceiling hinges on Smart spending most of his time on the other team’s largest player. Is it viable?

The decline of postups makes it conceivable against most opponents. Throw Smart on Rudy Gobert or DeAndre Jordan and their natural function is compromised. Paint protection matters, and there are certain matchups that will likely require a physical counterpart — Nikola Jokic, Joel Embiid, and Karl-Anthony Towns would have a field day — but the majority of teams don’t have a dominant back-to-the-basket monster. The hope is that crisp rotations that belie an unexpected double team can discombobulate them.

It’s the other end where benefits emerge. When downsized Boston will throw a spotlight on vulnerable big men who can’t race up and down the floor and are uncomfortable on the perimeter. All members of this unit can shoot, pass, and drive. Together they can be a Swiss-army knife that travels at light speed.

Whether it’s an eephus-pitch gimmick or a foundational part of their identity may decide if Boston reaches, exceeds, or falls short of its expectations for a second season in a row. It’s a fascinating conundrum for a deflated organization that’s in search of an edge. Trading for an established big who may be available and worthwhile (like Marc Gasol, Myles Turner/Domas Sabonis, Tristian Thompson, Cody Zeller, Andre Drummond, etc.) isn’t out of the question. But where things currently stand, this tiny, uber-talented group can be the solution to a problem that tortured the Celtics last season.