By Matthew Geagan, CBS Boston

BOSTON (CBS) — Marcus Smart is going to continue to be the longest-tenured member of the Celtics. That isn’t a bad thing, as much as some would tell you it is.

READ MORE: Fantasy Football Start Or Sit Week 2: Is Aaron Rodgers Due For A Big Bounceback Game?

Smart and the Celtics reportedly agreed to a four-year, $77.1 million extension on Monday night. Smart gets his contract and won’t be playing next season hunting for a deal, and the Celtics get a really important player on a really reasonable deal. It works for both parties in the here and now, and won’t handcuff the Celtics in the near future, either. It’s a solid win for Brad Stevens, who in a matter of hours after the season ended, went from coaching Smart to negotiating a deal with him.

While Jayson Tatum and Jaylen Brown make up the main foundation of the franchise, Smart is the jack post that helps hold it up. The extension should solidify him as the team’s starting point guard going forward, and new head coach Ime Udoka has already said that he is a fan of Smart. Udoka’s defensive approach should mesh extremely well with the way Smart plays on the floor, and hopefully the added responsibilities of being the primary ballhandler will shave off a few of those head-scratching shots that Smart is prone to firing up.

As far as the books go, Smart’s new paychecks won’t kick in until next season, so he doesn’t launch the Celtics into the tax threshold in 2021. The money is not as outlandish as most of the deals signed this summer, and if a big splash is still on the menu for next summer, Smart’s contract can be used to facilitate a trade. It’s a long-term commitment with an asterisk, with some wiggle room to move on should things trend south for any reason.

The deal was, of course, met with mixed reaction when the news broke. Most fans love Smart for his bulldog mentality and his inclination to sacrifice his body for any loose ball. “Winning plays” are part of his DNA, and at times last season, he looked like the only player fully engaged and committed to giving it his all every night.

READ MORE: Andrew Farrell Reflects On Setting A Number Of Revolution Records: 'I Just Love To Play'

None of that will change now that Smart has a new contract. If anything, he’ll be a happier fellow and even more committed to winning in green.

On the flip side, there are plenty of beefs that fans have with Smart. He can get a tad bit irritating at times, opting to hit the deck at the slightest amount of contact rather than bodying up on someone. He can drive you downright mad with his errant shot selection, heaving whatever the heck he wants at the worst possible times. And yes, there are the mental lapses where he just kinda forgets where he is and what the situation is. Those tend to pop up at all the wrong moments.

You take the good with the bad with Marcus Smart, and more times than not, the former outweighs the latter. That is the Marcus Smart experience. When he’s locked in on defense, he is a linebacker on the basketball floor. He’s still one of the best on-ball guys in the league and is willing to guard any position that he’s asked. He’s a two-time member of the All-Defensive First Team (2018-19, 2019-20), and will be motivated to return to that level next season and beyond.

A happy Smart will take the floor for Boston in a new role come October, part of the team’s soft reboot after such a disappointing campaign last season. The Celtics made a commitment to their longest-tenured player, giving him every opportunity to be a pierce of their foundation for the next five seasons. And if it doesn’t work out this year, the contract will be a valuable asset that could be used in a big trade.

But for now, Smart is a part of Boston’s core. Udoka is going to put more responsibility in his hands as the team’s starting point guard, and Stevens made good on his “love and trust” of the player. Now it will be up to Smart live up to his end of the bargain.

MORE NEWS: The List Of Six Rookie Quarterbacks Who Have Beaten Bill Belichick's Patriots Is Insane