WALTHAM, Mass. – Marcus Smart has gotten a first-person look at his team’s defensive abilities throughout the last week.

He hasn’t enjoyed the view.

Not because his Celtics are incapable of defending at a high level. No, it’s the exact opposite: he’s been turning the ball over more often than normal because Boston’s defense, from top to bottom, is so long and athletic.

“The thing about [length] is guys, until they put their arms up, they don’t look as long,” Smart said following Tuesday afternoon’s practice. “Like (Jayson) Tatum – he’s one of those guys. He’s just standing in front of you and you’re like, ‘OK,’ and then he puts his arms out and his wingspan is crazy and he starts getting deflections that normal guys probably couldn’t get.”

Smart has witnessed the impact of Boston’s length and athleticism for an entire week of practice. He has seen all too often the lack of passing lanes, the amount of deflections caused, and the driving angles that have been taken away by Boston’s defense.

The Charlotte Hornets, on the other hand, just got their first look Monday night. They didn’t enjoy the view either.

Charlotte, in its opening game of the preseason, committed 19 turnovers while shooting only 37.5 percent from the floor en route to 82 points. The Hornets struggled through 48 minutes, to put it lightly.

Boston won’t necessarily force those types of numbers all season long, but Monday’s performance was an impressive first impression by the team’s defense.

“We had a couple of sequences where everyone had their arms up and you could just tell that Charlotte couldn’t go anywhere,” Smart stated with a hint of bravado, “and they looked at it and they just seemed baffled by it.”

Tuesday’s film session affirmed the message Brad Stevens has been relaying to his long and athletic team about that very fact throughout the preseason.

“That’s what Stevens has been preaching to us,” Smart, who came off the bench to tally nine points and four rebounds, added. “Usually when we’re all out here, all of these guys are long and athletic – use that to your advantage.”

Al Horford isn’t the most athletic player on Boston’s roster, but he sure is one of the longer ones. Horford, who owns a wingspan of 7-foot-1, has been watching Boston’s defense operate from the interior, and he believes the C’s could be scary good at that end by the time the postseason arrives.

“I think that we can be a really good defensive team,” Horford said. “I don’t think people realize how good of a defender a guy like Gordon (Hayward) is, for example, what he brings and the toughness. He’s able to block shots as well.

“By the end of the season, we have a chance to be a really good defensive team.”

Notice that Horford, a seasoned veteran leader, isn’t putting the pressure on Boston to come out of the gates this month firing on all cylinders at the defensive end of the court. He understands that this is a new team, and new teams take time to mold together.

But he, as well as Smart, have seen firsthand just how impressive this defense can be.

Boston could very well have players 6-foot-7 or taller starting from shooting guard on down to the center position. There are fewer than a handful of teams in the league that can make such a claim – Golden State, Milwaukee and Toronto come to mind – and no one enjoys facing those teams.

Add the C’s to that list, because in Boston, the view will consist of a bunch of arms and hands, and of very few open lanes.