Hot-then-cool Trail Blazers are back to warm playoff feeling

The Portland Trail Blazers expected to make the playoffs. They never envisioned practically wrapping up a spot by the day after Christmas.

A 24-5 start gave them the best record in the NBA and made them the league’s biggest marvel.

“I would lie,” center Robin Lopez admitted this week, “if I said the beginning of the season didn’t surprise me.”

The next three months would be startling in a different sort of way. The Blazers have gone 25-23 since their world-beater days, though they’re on the verge of clinching their first playoff berth since 2011 and still have a chance to secure home-court advantage in the first round.

Their prolonged struggles may have come with a lesson that could extend Portland’s postseason life expectancy: For all of their offensive buoyancy, it’s often the Blazers’ defense that keeps them afloat.

Portland (49-28) is 24-4 when holding other teams under 100 points and, perhaps more tellingly, has won 24 games when opponents shoot below 45%. The latter statistic ties the Blazers for the league lead with the Chicago Bulls, who treat every point allowed as a personal affront.

“We’ve played good defense in stretches,” Portland Coach Terry Stotts said, “but we need to sustain it for longer periods.”

The Blazers were mostly about offensive proficiency in the season’s early going. They led the NBA in three-point accuracy for months and at one point scored 100 or more points in 18 consecutive games.

It was a dizzying display for a team that had gone 33-49 the previous season and had not drastically changed its roster.

General Manager Neil Olshey added quality depth with the acquisitions of Mo Williams, Thomas Robinson and Dorell Wright but replaced only one starter, substituting Lopez for the departed J.J. Hickson.

That left the Blazers with a starting lineup whose average age was 25.8 and a roster with eight players in their first or second years in the NBA.

The kids were ready for the challenge. All-Star forward LaMarcus Aldridge, who at 28 qualifies as the old-timer of the bunch, realized it even before the season.

“When I came into training camp, I could tell that everybody had the mind-set of ‘Let’s win’ and I could see how unselfish everyone was and I thought Neil did a great job of bringing in pieces that complemented everybody else,” Aldridge said. “I had a feeling early that this team would be special.”

Point guard Damian Lillard became an All-Star in only his second NBA season and has combined with fellow starters Wesley Matthews and Nicolas Batum to make 532 three-pointers, more than the total of 11 teams.

Lopez has 29 double-doubles and is averaging 8.6 rebounds per game, 3.0 more than his previous best. Aldridge continues to make analytics proponents look foolish, burying his defender beneath an avalanche of mid-range jumpers.

Meanwhile, Williams has efficiently run a vastly improved second unit, leading the league with 312 assists off the bench.

“I think you can make the case that seven or eight guys are having career years, we’ve been very healthy, we have a good group that plays together and plays the right way,” Stotts said. “We have good chemistry and we’ve got talented players.”

It helps that they’ve been able to keep them together on the court, for the most part. The Blazers had the same starting lineup for the first 53 games and have used only two different starting lineups all season. Aldridge is the only starter to be sidelined, missing 12 games because of injuries.

Portland has gone 4-1 since he returned from a bruised lower back late last month. Defense has sparked the resurgence, with the Blazers holding Atlanta to 85 points, Chicago to 74 and Memphis to 98.

With five games left in the regular season, the Blazers are only two games behind the Houston Rockets for the No. 4 seeding in the Western Conference and home-court advantage in the first round.

Have they already exceeded what they thought was possible this season?

“We don’t know where we’re going to end,” Williams said, “so that’s not a good question to answer right now.”

ben.bolch@latimes.com

Twitter: @latbbolch