Jaylen Brown and the Boston Celtics agreed to a four-year, $115 million contract extension on Monday, and this is honestly surprising because this is not how the Celtics typically operate.

Handing out contract extensions to players on rookie deals is not something Danny Ainge usually does.

The Celtics didn't do it with Kelly Olynyk. They didn't do it with Marcus Smart. They didn't do it with Terry Rozier.

Of course, the Celtics and Smart ultimately struck a four-year deal in free agency during the summer of 2018, but both Olynyk and Rozier walked. Ainge not immediately extending Smart had me doubting he would do it for Brown, but that turned out to be wrong.

Obviously, Olynyk and Rozier are slightly different cases, because Brown is clearly a better player with a higher ceiling than both of those guys (although Olynyk is a bit underrated).

So, it's entirely possible that Ainge simply saw value in Brown that he could not pass up, so he just wanted to lock him up now.

Brown is an interesting prospect, to say the least.

He turns 23 years old on Oct. 24, so there is still plenty of room for him to grow. What we do know thus far is that he is a terrific athlete who plays both ends of the floor. He is a decent shooter, although his free-throw shooting needs work.

As far as his basketball IQ? It's questionable at times, which is the main drawback when it comes to Brown. As a result, his consistency has suffered.

That being said, with Kyrie Irving gone and numerous others players such as Al Horford, Marcus Morris, Rozier and Aron Baynes also playing elsewhere this season, Brown's role should grow significantly, so this may be his time to shine.

Remember: Brown had his coming out party with Irving and Gordon Hayward sidelined during the 2018 playoffs, so perhaps all he needs is a bigger opportunity.

Still, that doesn't mean he will suddenly develop a go-to move or that things will just “click” out of the blue for the young guard.

Regardless, it's apparent that Ainge and the Celtics' front office likes what they see from Brown. Based on how good Boston's organization usually is when it comes to talent evaluation, we have no reason to doubt it.

In a changing NBA landscape that values floor spacing and defensive versatility above all else, you can see where Brown fits into the equation.

While he isn't a knockdown 3-point shooter, he is decent, shooting 36.5 percent from deep for his career. He is also a guy who can guard multiple positions effectively, which is inherently valuable in and of itself and is also a big reason why the Celtics liked Romeo Langford so much on draft night.

Basically, Brown does have a decent ceiling. While he may not have the superstar potential of Jayson Tatum, he does seem to have the potential to make some All-Star teams. If Ainge does see that, you can understand why he wouldn't want Brown to get to free agency next summer.

Anyway, it seems like the Celtics have identified a key cog in what they hope is a successful future.

Hopefully, Brown can deliver.