Few teams had as many peaks and valleys over the course of 2018-19 as the Boston Celtics.

From Kyrie Irving saying he'd be back next season and The Ringer's Bill Simmons predicting 67 wins to Kyrie backpedaling on his return and the team falling around 10 wins shy of its preseason over/under, this was about as close to the up-and-down cliche as Boston could get.

On Sunday, the Celtics completed their sweep of the Indiana Pacers to punctuate an ascent that started at the end of March. Following a four-game losing streak—their second since the All-Star break—the Cs won six of their last eight games, including two over the Pacers, to secure fourth place and home-court advantage in the first round.

Over the last month, the Celtics have started to remind us why so many were high on them heading into this season. In the first-round series against Indiana, Boston allowed just 95.8 points per 100 possessions, according to NBA.com. For perspective, the Pacers scored 109.3 points per 100 possessions over the course of the regular season—108.8 since Victor Oladipo's season-ending injury.

On the other end of the floor, the Celtics aren't scoring as effectively as they did in the regular season, but some important individual players are locking in.

Boston pretty much knows what it's going to get out of Irving. His 22.5 points per game in the first-round sweep were nice, but it's the three wings who will be critical going forward.

Against the Pacers, Jayson Tatum averaged 19.3 points with a 57.9 effective field-goal percentage. Jaylen Brown was at 11 and 69, respectively. And in the series-clinching Game 4, Gordon Hayward calmly and coolly worked his way to 20 points on 7-of-9 shooting, including a 3-of-3 performance from three.

Every bit as encouraging as the numbers are sights like this one shared by Dime, during which Hayward elevated like his 2016-17 self:

No, that bucket didn't count (due to an offensive foul), but Hayward playing with that level of aggression and explosiveness could raise Boston's ceiling.

Back in December, The Boston Herald's Mark Murphy wrote, "Though Hayward has engineered some bright flashbacks to his pre-injury self...his progress still charts like the stock market. Ups are followed by dips, with recoveries, and more dips."

But since the All-Star break (and including the playoffs), Hayward has averaged 12.2 points, 4.3 rebounds and 2.9 assists—16.6 points, 5.8 rebounds and 3.9 assists per 36 minutes—while shooting 53.9 percent from the field. Over that span, his creation off the bench has helped Boston outscore opponents by 85 points in 608 minutes when he's on the floor. The Celtics are minus-63 in all other minutes.

This is closer to what Celtics fans must have imagined when they began the season with Hayward, Brown and Tatum all starting. Boston appeared as well-equipped as anyone for the ongoing positionless revolution.

In September, Celtics Blog's Greg Brueck-Cassoli shared video of head coach Brad Stevens talking about this vision:

Over Hayward's first 15 games, all starts, Boston was minus-16 in the 163 minutes during which Hayward, Tatum and Brown all shared the floor. Add Irving and Al Horford, and the dream lineup was minus-7 in 137 minutes.

Now, as Hayward rounds into form, the positionless trio appears to be doing the same. Since Feb. 21, Boston is plus-5.7 points per 48 minutes when those three are featured (regular season and postseason combined).

The versatility that lineup provides will be critical as the Celtics head into a second-round matchup with, presumably, the regular season's best team.

The Milwaukee Bucks, currently leading the No. 8 Detroit Pistons 3-0 in their Round 1 series, feature MVP candidate Giannis Antetokounmpo. If Boston was poised to be the positionless era's quintessential team, Giannis is on track to be its quintessential player.

His stat lines look like something out of a Kareem Abdul-Jabbar game log, only with more assists. He dunks about as often as prime Shaquille O'Neal. And since Feb. 1, he's shooting just under 33 percent from three. No, that's not great. But with everything else he does, being forced to at least close out on his jumper just isn't fair.

In the regular season, Giannis averaged 31 points with a 65.8 true shooting percentage against Boston, but only one of those games came after the All-Star break. An increasingly comfortable Hayward should allow the Celtics to play more wing-heavy minutes against Milwaukee.

Those will be key. You need to throw as many switchable defenders at Giannis as possible. With those three and Horford, Boston can play more than most teams.

During last year's playoffs, the Celtics used multiple defenders and a human wall around the paint to contain Philadelphia 76ers point guard Ben Simmons, and the strategy worked to great effect. That Philly team was not these Bucks. Simmons is not Giannis.

But Boston has the personnel to at least make things difficult on the East's favorites. And if the Celtics keep climbing the way they have for the last month, they'll continue looking more and more like the title contenders most expected to see all along.