Let me preface this by saying that the Boston Celtics were supposed to beat the Indiana Pacers. They were clearly the more talented team, and even though they won just one more game during the regular season, it as blatantly obvious that they were vastly superior.

However, there weren't many who expected the Celtics to sweep this gritty Pacers team, a ballclub that was contending for a three-seed in the Eastern Conference up until the final two weeks or so of the regular season.

But, that is exactly what Boston did on Sunday, coming up with a 110-106 victory at Bankers Life Fieldhouse to complete a four-game sweep of Indiana and advance to the second round where the C's await an inevitable matchup with the Milwaukee Bucks.

The Celtics moving on is not a surprise, but we can't ignore some of the developments we saw in this series.

First and foremost, Boston's fourth-quarter execution was phenomenal.

This was something the C's struggled with all year. They simply could not close out games on a consistent basis, and they lost countless contests as a result of wetting themselves over the final couple of minutes.

That certainly did not happen in this series, as the Celtics knocked fourth quarters out of the park when they had to in Games 2, 3 and 4, making all of the big plays on both ends of the floor to ensure victories.

Kyrie Irving, Celtics

And the best part was that it came from all different sources.

In Game 2, it was Al Horford coming up with big defensive stops, Jayson Tatum making several huge buckets, and Gordon Hayward making all of the right plays down the stretch.

In Game 3, it was Kyrie Irving being Kyrie Irving, Horford draining some big shots, and the Celtics' defense locking in as a whole.

Then, in Game 4, it was Hayward, the prodigal son who had his first truly big moment as a Celtic, nailing a couple of three-pointers and converting a three-point play in the closing stretch to preserve a series-ending win.

Basically, Boston got production from everywhere late in games, and on the road, no less. Remember: the C's were allergic to road victories last spring, collecting just one win away from the friendly confines of TD Garden last postseason. This year, they have already eclipsed that total with a pair of road triumphs against the Pacers.

Kyrie Irving, Celtics

Again, all of this did come against an Indiana team that realistically had no shot of beating Boston four out of seven times, but regardless of the opponent, the Celtics' magnificent late-game execution is nothing to sneeze at.

After all, this was the type of late-game magic that was missing against teams like the Phoenix Suns and Charlotte Hornets during the regular season. Had Boston played this way in final frames back in January, perhaps it would be a 2 or a 3 seed rather than a 4.

The Celtics' ability to put the Pacers away consistently in this sweep bodes very well for the team moving forward, as it seems that Boston has established a formula of how to close out games.

To be perfectly honest, it's entirely possible that formula was there all season to begin with, but the C's, maddeningly, did not appear to take things seriously 100 percent of the time from October through early April.

Al Horford, Celtics

Let's also keep in mind that the Celtics have some experience in these moments.

A year ago, Boston made it all the way to Game 7 of the Eastern Conference Finals without Irving and Hayward, and it was largely due to the fact that its fourth-quarter execution was remarkable for a club that young. Of course, it didn't exactly translate on to the road save for one game in Philadelphia, but just having that experience is clearly paying dividends now, as youngsters like Tatum and Jaylen Brown are certainly wiser now than they were 12 months ago.

That's another thing: Tatum and Brown were fantastic in this series. Tatum averaged a cool 19.3 points per game while amassing a true-shooting percentage of 59.7 percent, and while Brown's offensive numbers don't look great, he was phenomenal defensively, and he made all of the right plays on both ends.

Even Terry Rozier seemed to awake from his season-long slumber, albeit quietly, staying within himself, playing terrific defense and not taking—let's just come right out and say it—silly shots.

Jayson Tatum, Celtics

As a team, the Celtics were outstanding defensively, demonstrating their ability to switch everything while also mucking the game up with bruisers like Aron Baynes and Marcus Morris. All of that came without Marcus Smart, too, who might be back at some point during the second round.

You know all of those problems Boston was having during the regular season? Those identity issues? Those moments in fourth periods where the C's looked completely clueless?

Those are a distant memory now.

Of course, the Celtics are about to face a much stiffer test. The 60-win Bucks are not the Victor Oladipo-less Pacers. But Boston is certainly better-equipped to face Milwaukee now than it was two months ago.

Irving seems happy. Hayward looks great. Tatum and Brown look seasoned. Horford and Morris bring veteran savvy. And Brad Stevens is ready to add to his resume.

The Celtics seem to be putting it all together, and that's bad news for the rest of the East. The Pacers just found that out the hard way. Could the Bucks be next?