The last time the Boston Celtics faced a decision on an injured guard’s impending, potentially expensive free agency, Danny Ainge sold high on Isaiah Thomas.

This summer, the Celtics face a similar financial decision with restricted free agent Marcus Smart. The torn ligament he suffered in the March 11 loss to the Indiana Pacers isn’t as severe as a torn hip, but then there’s the matter of his broken jumper.

Offense

Kyrie Irving, Marcus Smart

If you haven't watched Marcus Smart play, you might think he's a scrub simply by glancing at the box score. His 36.7 percent field goal percentage ranks 262nd amongst the 269 players who have appeared in at least 50 games this season. Last year, he was one of only 10 players in NBA history to shoot under 29 percent on at least 4.0 attempts per game from downtown.

This year? Well, he's raised the bar he put at an ant's height by becoming one of 26 players in history to take at least 4.5 three's per game and connect on under 31 percent of those shots.

Even though he's one of, if not THE worst three-point shooter of all time in a league that values threes more than ever, his nightly impact on a game goes a lot further than reading the box scores on ESPN.com.

Offensively, Synergy Sports grades him in the average range in points per possession as a pick-and-roll ball handler (0.772), a spot-up shooter (0.91) and on isolation plays (0.787). Those three play types are significant because they make up 58.7 percent of his possessions.

Outside of scoring, he's a very willing screener who uses his wide shoulders to get his teammates open to score. This allows players like Kyrie Irving, Jayson Tatum or Terry Rozier to focus their energy on scoring the basketball instead of getting open. Smart also takes pretty good care of the ball, averaging a 2.01 assist-to-turnover ratio, which is comparable to Stephen Curry (2.03) or James Harden (2.04), but obviously on a much lower usage scale.

But enough about his offense. Defense is what's going to make him some green this offseason.

Defense

Marcus Smart
CP

Marcus Smart attacks the defensive end of the floor like a pit bull. He's not always the biggest or fastest, but he's a strong mother fricker who refuses to take crap from anyone. Even at 6-foot-4, he can guard four positions. And on some nights, he might even be able to guard the opposing team’s center.

On the perimeter, he uses sound fundamentals to stay deep into his defensive stance which allows him to maximize his lateral quickness and stay in front of opposing players. Even if he does get beat, he understands how to legally use his strength to propel himself back into the play and lets his lightning-quick and thunder-strong hands do the rest.

According to CleaningTheGlass.com, he's ranked in at least the 92nd percentile or above in steal percentage every year except this one (80th percentile) and has never been above the 55th percentile in foul percentage. That's an amazing ratio considering typically the more steals a player has, the more fouls they're likely to accrue.

Even when he gets matched up against bigger players, Smart gives them hell by knowing exactly how to use his strength and vertically to his best advantage. According to Synergy, he ranks in the 61st percentile in post-up points per possession (0.836), which is better than guys who are known for their post defense like Taj Gibson (0.842) and Bismack Biyombo (0.85).

This unique grit and versatility is what teams are looking for more of in the NBA today. This brings up an interesting scenario about the Celtics' willingness, ability, and capacity to retain him on next year and beyond.

Free agency overview

Marcus Smart

Smart is set to be a restricted free agent once the season is over and will have a qualifying offer just a hair above $6 million. Fortunately for the former Oklahoma State Cowboy, he will command an annual salary much higher than that, if not at least double, beginning with the 2018-19 season.

Boston's roster will mostly stay intact barring a legion of trades (which is never out of the realm of possibilities with Danny Ainge), as Smart and Aron Baynes are the only two rotation players not under contract for next year. With the salary cap projected to be at $101 million, they will already be a bit over at $107.4 million, but they'll still have plenty of room to work with under the dreaded luxury tax ($123 million).

The Celtics and Ainge will likely slow-play the situation with Smart for several reasons. First, because he's a restricted free agent, Boston can match any contract he signs with another team. This means they don't have to go overboard by signing him to a huge deal if he's not going to get anything close to that money elsewhere.

Second, after the money splurge in recent years, there are very few teams out there with available cap space to make a serious run for Smart's services. Most of the teams will only have the mid-level exception ($8.5 million) to use. If that's the case, Ainge is likely to match it without thinking twice.

However, there are a few teams with enough cap space to make a bidding war interesting.

Philadelphia 76ers

The Philadelphia 76ers will have the contracts of J.J. Redick ($23 million), Amir Johnson ($11 million) and Trevor Booker ($9 million) coming off the books to help offset Joel Embiid's $19 million raise and might want to use some of that money on a long-term solution. Although Smart would be a far from perfect fit in the backcourt alongside fellow brick-shooter Ben Simmons, it would provide them with an intriguing defensive backcourt. And besides, it would be a win-win, as they'd strengthen their team and weaken their division rival.

Indiana Pacers

The Indiana Pacers will have a lot of opportunities to create some cap space with the pending contracts of Thaddeus Young ($13.7 million), Bojan Bogdanovic ($10.5 million), Darren Collison ($10 million), Cory Joseph ($7.9 million) and Lance Stephenson ($4.4 million).

Young's and Joseph's are player options which are likely to be accepted. However, Bogdanovic and Collison each have non-guaranteed deals while Stephenson's is a team option.

With Indiana being one of this year's surprise teams, they could be looking to take another step forward next season with the addition of Smart. He'd fit pretty well next to Oladipo and Myles Turner’s ability to stretch the floor, allowing ‘Dipo to focus more on his offensive responsibilities.

Los Angeles Lakers

A third team to look out for is the Los Angeles Lakers. They’ll have a plethora of cap space available and will obviously be aiming at the top of the mountain for their free agents. But if they miss, they might lower their sights to a player like Smart who can be a great backcourt mate next to Lonzo Ball and help bring some toughness back to the Staples Center.

Unless one of these teams offers some ridiculous money to Smart, the Celtics are likely to bring him back next season, which is absolutely what they should do.

His versatility is what Brad Stevens is all about and a big reason they've had such a high-level of success on the defensive end of the floor this season. When Smart sits, Boston's defensive rating is 103.1, which would be the fourth-best in the NBA. However, when he's on the floor they kick it up another notch and tally a defensive rating of 99.4, which would be the best in the NBA by almost two whole points.

Defining value is no easy feat in the NBA. That Marcus Smart struggles in some of the most obvious places we search for it makes it all the more difficult.

But Smart is beloved by his teammates, coaches and front office staff in Boston. The Celtics are better when he plays. Outside a completely outrageous offer, there's no logical reason why he shouldn't be back in a Celtics' uniform next season.