By Matthew Geagan, CBS Boston

BOSTON (CBS) — There is nothing quite like the emotional roller coaster one rides on when Marcus Smart rears back and gets ready to fire up a shot. You either feel great joy or crippling anguish when Smart gets into a flow.

Smart does get hot from downtown, and when he does, look out. The Celtics guard can knock down shots in a hurry. But when he’s cold… well let’s just say a cold hand won’t keep Smart from acting like a flamethrower on the floor, and that can be a tad bit aggravating. It’s tough to watch Smart heave up a bad shot when Jayson Tatum is wide open in the corner.

With Kemba Walker sidelined for the opening weeks of the 2020-21 season, there is a lot more on Smart’s plate heading into the new campaign. Smart knows he has to be at his best in order for the Celtics to jump out to a good start, and as the team’s likely starting point guard, it will be his job to get the offense flowing and get everyone involved.

But that doesn’t mean Smart won’t be looking for his shot. And this year, it sounds like he’ll be looking for his best shot. During a Monday chat with reporters, Smart said that shot selection was his biggest focus during the brief offseason.

Why?

“Because when I take great shots, I’m a great shooter,” Smart said confidently.

Smart’s shot selection isn’t always the greatest, but anyone who has experienced Marcus Smart in the Celtics offense knows that the laws of averages (or really, the laws of physics) do not apply to Marcus Smart. A good shot for everyone else isn’t always a good shot for Smart, and vice versa.

Smart tends to sink the difficult shots that look like they have no chance at going in, and he tends to miss the open ones. There really isn’t any explaining it, aside from it all just being part of what makes Marcus Smart who he is.

Smart did not enter the NBA a great shooter. For the first two years of his career, he was one of the worst in the NBA at hitting shots from deep. But all of the misses did not deter Smart from firing up shots from downtown; he’s never attempted fewer than four threes per game in any season of his career.

All of those shots did pay off, too. Smart has turned into a respectable three-point shooter, hitting a career-best 36 percent from downtown two seasons ago. He attempted two more threes per game last season (a career-high 6.6 per contest) and saw his percentage dip 34 percent from deep.

Where does Smart do his damage? He is not particularly strong from the corners, hitting just 33 percent of his shots from the right or the left. But he hit 42 percent of his step-back threes and 43 percent of his pull-up threes.

But placement on the court isn’t the biggest factor for Smart taking a shot. Where he needs to improve the most is his timing. He can’t be chucking up shots with 20 seconds on the shot clock before anyone has a chance to rebound a potential miss, and he can’t force his own shot if he has teammates open elsewhere. While a Smart make from deep can spark a Boston run, a poorly timed forced heave can easily derail a game.

But if Smart is open, he’s going to shoot. And really, we should all know that by now.

“If I’m open, I’m definitely shooting the ball,” he said Monday. “My teammates, the coaches staff, definitely told me catch and shoot. If you’re open, shoot it.”

Celtics head coach Brad Stevens is happy to give Smart the green light, but he’s also highlighted the importance of Smart quarterbacking the entire Boston offense with Walker sidelined.

“He’s got to continue to build off of the threat he is, and at the same time, we need him to organize us and help run us, especially while Kemba is out,” Stevens said Monday. “There’s even more of a responsibility to get us organized as a team. Guys are going to have nights when they make shots, don’t make shots and if they are wide open, inside-out shots, you have to shoot those.

“At the same time, I think he can get everybody where they need to be. He’s a much improved shooter but he’s also an outstanding playmaker,” added Stevens. “I’ve told him we’ve talked a lot about increasing the efficiency of our team and his ability to make plays for others is a big part of that, putting guys in the right spots to soar with their strengths.”

Smart is ready to run the show on offense, pointing to his 4.8 assists per game for Boston in the NBA bubble in Orlando. He dished out a career-high 4.9 assists per game for the season.

“I just need to continue to keep making plays for others and create for myself,” he said. “We have other guys out here who work just as hard, who have been working to grasp their moment. … It sucks to have Kemba out but that means everyone has to step up.”