The Bucks shouldn’t be in this situation right now. Giannis Antetokounmpo is one of the NBA’s best players and their roster has shown promise in recent years, yet they trail 3–2 in a first-round playoff series against the injury-depleted Celtics after losing 92–87 on Tuesday. In Game 5, Milwaukee’s best players got beat by Boston reserves who have barely played in the past month: Marcus Smart and Semi Ojeleye. They outhustled and outmuscled the Bucks; the game was emblematic of Boston’s season.

The NBA Playoffs Check out The Ringer’s coverage of the 2018 NBA playoffs

Playoff series are like chess matches, with adjustments coming game to game, or even possession to possession. It’s been interesting to watch the noticeable lineup tweaks that the coaching staffs — led by Celtics coach Brad Stevens and Bucks interim coach Joe Prunty — have made during this series.

The Bucks didn’t turn to lineups with Giannis at center until there was 3:11 left in the fourth quarter of Game 1; in Game 2 they went to it earlier. But Stevens had his countermove ready: When the Bucks went small, the Celtics went big with Greg Monroe, who bullied Milwaukee inside and rendered the lineup ineffective. In Game 3, Prunty doubled down by replacing John Henson — who was sidelined with a sore back — with Thon Maker, who played like the Kevin Garnett of a basketball tribute band. Monroe became unplayable because of Milwaukee’s sheer speed advantage, and all of sudden the series was tied up. In Game 5, Stevens started Ojeleye at power forward, aligning Aron Baynes’s minutes with Maker’s off the bench. Stevens’s adjustment paid off: Baynes beasted Maker in the first half. Prunty countered by starting Maker in the second, and played Antetokounmpo for the final 24 minutes rather than spelling him with center Tyler Zeller. It wasn’t enough.

But the biggest differentiators in Game 5, and perhaps the entire series, are Smart and Ojeleye. Smart, who played his first game after missing six weeks while recovering from surgery to repair a torn ligament in his right hand, had just nine points on 2-for-7 shooting with four assists and five turnovers. Ojeleye, the no. 37 pick in 2017, received his first NBA start and logged no steals or blocks over 31 minutes. But as is usually the case, box score numbers don’t properly reflect defensive impact.

The return of Smart and the emergence of Ojeleye were integral to Boston’s Game 5 victory. Smart is adrenaline incarnate; 40 seconds after checking in he struck like a cobra to chase down a loose ball, and minutes later he stretched to deflect an alley-oop away from Giannis.

This is who Smart is as a player. Stevens has never hesitated to stick him on meaty bigs like Paul Millsap or freaky ones like Kristaps Porzingis. He’s 6-foot-3, but he has a 6-foot-9 wingspan and the muscular frame of an NFL pass rusher. Traditional positional labels such as “guard” and “forward” are antiquated because of players like Smart. Late in the fourth quarter, Smart bookended his performance by once again playing rim protector. He swatted away a Giannis layup with 3:29 to go, then a little over a minute later stripped Khris Middleton before altering Shabazz Muhammad’s shot.

Hustle and grit are intangible qualities, but Smart is also one of the game’s best man-to-man defenders. All along the way, Smart did all the little things and made life hard on Middleton, who had scorched the Celtics all series by getting to the basket without much resistance and sinking countless contested 3s — like his shot with half a second left in Game 1 to send the game to overtime. Middleton still scored 23 points in Game 5, but he was inefficient until his percentages were somewhat salvaged by two Hail Mary 3s made in the final minute. Smart spent 21 of his 54 defensive possessions on Middleton and kept him away from the basket.

Middleton wasn’t the only Bucks star rattled by his matchup. Antetokounmpo attempted only 10 shots in Game 5, which seems like an unforgivable sin in a must-win situation. But Ojeleye, a brick house of a man, played stout defense against Antetokounmpo and deterred him from finding his spots perhaps better than any player has all season. Ojeleye might be uniquely equipped to handle a player of Giannis’s dimensions: He’s as agile as he is jacked, which made the Greek Freak’s drives to the rim look like he was pushing against a concrete wall.

Here are all Ojeleye’s notable possessions defending Antetokounmpo, most of which came in the second half:

The first clip sums it up: The Bucks were feeding Giannis, but he wasn’t biting. Ojeleye mirrored his movements and forced passes, and the Celtics collectively finished possessions with aggressive, sound rotations. It’s still odd to see Giannis bounce off Ojeleye and get forced to take awkward fadeaways; usually he’s taking advantage of any height mismatch, but against Ojeleye, he’s actually punching above his weight class.

Prunty is a convenient scapegoat because, from an outside perspective, it’s on the coach to get his star player more shots. But it’s not like Giannis didn’t get opportunities; in fact, he logged more touches (93) than he had in regulation of any other game this series. And it’s not like the Bucks didn’t make any adjustments, either. They ran on-ball screens using Eric Bledsoe or Matthew Dellavedova to try to get Giannis switched onto one of Boston’s guards— Terry Rozier or Shane Larkin — but rather than switch, the Celtics blitzed.

Giannis told reporters after the game that it’s on him to be more aggressive. But even if Giannis were to channel LeBron in his Game 6 performance against Boston in 2012, the rest of the roster would still need to come through. Game 5 featured one disappointment after another from the Milwaukee reserves, as has the whole series. Tony Snell, who is owed $34.2 million through the 2020–21 season, is a disappearing act; he shot 0-for-5 from 3 in Game 5. All were open jumpers. Dellavedova is feisty, but he also can’t seem to hit an open jumper. Malcolm Brogdon has struggled since returning from a 30-game absence due to a quad injury.

Then there’s Bledsoe, who has consistently failed to get his hand up and allowed countless backdoor cuts like he’s addicted to giving away easy buckets.

Bledsoe made a few good man-to-man defensive plays, but when he’s off the ball it’s like he’d rather be at a hair salon. In one of the clips above, he loses sight of Jayson Tatum, leading to a drawn foul. If it were to happen again, it could turn into a kick-out pass for an open 3. And in the other clip, he fails to recognize the off-ball switch and doesn’t even try to contest the shot. Bledsoe’s off-ball mistakes have snowballed into a point barrage.

It doesn’t help that Bledsoe jacks up far too many contested pull-ups from midrange less than 10 seconds into the shot clock.

Bledsoe developed into a high-level pick-and-roll player in Phoenix, but he still too often settles for poor shots or makes reckless passes. It might seem like Bledsoe is a lost cause, but there’s no doubt he has athletic talents. He was an excellent all-around defender many moons ago as a young player with the Clippers. The Bucks traded a protected 2019 first-rounder that would lose its protections in 2021 for Bledsoe; they need to find a way to mine his dormant defensive talent.

More immediately, the Bucks need to continue making strategic changes to extend the series. I’ll be watching how they defend Smart, who, in Game 5, was wearing a splint on his shooting hand and was reluctant to launch shots from outside the paint (both of his 3s came with less than five seconds left on the shot clock). It’s abnormal for Smart to hesitate when he typically launches at a frustrating clip, yet the Bucks defended him as they normally would any other guard. Milwaukee instructs its guards to fight over screens and its big man to show. Smart took advantage by finding open teammates.

This is simply how the Bucks have played defense all season, and while it’s unfair to expect a young team to drastically tweak its approach, Game 6 will call for drastic measures. Smart is only a career 29.3 percent 3-point shooter, and it’s conceivable that he’s even less comfortable wearing the splint. If they tweak their system to have guards go under and have the screen defender drop, perhaps they’ll bait Smart into taking low-quality pull-ups, while also limiting passing lanes.

Even further, the Bucks could have Smart’s defender sag off of him and operate much like the Heat tried to against Ben Simmons in Game 1 of the Miami-Philly series, or like teams used to do against Boston-era Rajon Rondo. But Smart isn’t on the same level as an attacker or playmaker. Until Smart proves he can hit any shot outside the restricted area, it’s worth treating him like a nonshooter. And if going under screens or giving him space to shoot were to theoretically work, the Celtics might be forced to run more of their offense through other players, which would put Smart off the ball and enable the Bucks to give him the Tony Allen treatment. The Pelicans experienced success having Anthony Davis sag off of Al-Farouq Aminu and into a free safety role, where he helped on cutters and attackers. Aminu hit his open 3s, but the rest of the team didn’t. Boston is already limited offensively; if Milwaukee can suffocate cutting and slashing lanes, it’ll be even harder for the Celtics to score. Maybe a way to get Bledsoe engaged on defense is to empower him as a defensive roamer who helps off of Smart and attempts to wreak havoc in the passing lanes and force turnovers.

It’s not as if the Bucks ever hesitate to double-team. But they need to be more selective about it. When the Celtics feed Al Horford on the post, the Bucks are far too eager to double him. Horford is one of the NBA’s best passing playmakers at his position. Throwing long limbs at him isn’t as effective as it would be for most centers. He’ll still find the open shooter.

Jabari Parker has largely been inept defensively this series (and his entire career). It’s one of the primary reasons, aside from his two torn ACLs, that the Bucks haven’t quite been able to maximize their length on defense. In the clip above, Parker leaves Jaylen Brown open to double Horford, which leads to an easy Brown 3-pointer. But it’s hard to blame Parker here despite his aimlessness, because the Bucks have routinely doubled Horford in the post, regardless of the defender. It’s time to stop. Horford scored a measly 0.82 points per possession on post-ups this season, but his post passes led to 1.19 points per possession, according to Synergy Sports. Unless they’re helping off of Smart, the Bucks need to live with the results of the single-coverage matchup on Horford.

To the surprise of nobody, Stevens is winning the coaching battle with Prunty. The series isn’t over, but the fact the Celtics have taken control of the series by stonewalling the two best Bucks with a rookie second-rounder and a guy who hasn’t played in six weeks perhaps says less about the Celtics and more about how far away Milwaukee is from true contention.