What does Garrison Mathews bring to the table?

Quietly on Friday, the Boston Celtics announced the training camp and non-guaranteed signing of Garrison Mathews, formerly of the Washington Wizards. With little promise of a roster spot, the move brought a giant smile to my face.

Mathews is elite in his role and worthy of the 15th position on the Celtics bench. There’s zero risk involved for Brad Stevens and the Celtics with the non-guaranteed nature of the deal, and far more upside than those outside of DC have seen. With Mathews also eligible for a two-way contract, my odds are on him sticking around in Boston longer than just the next month.

Standing 6’5”, Mathews will turn 25 before November arrives, meaning he’s no spring chicken despite being a newer name in the league. But Mathews is proficient in a niche area that is vital in today’s game: he’s a specialty 3-point shooter.

Over two NBA seasons, Mathews has shot 95-244 (38.9%) from deep. He has five-times more threes (95) than career turnovers (18). A prolific scorer at Lipscomb and former Atlantic Sun Player of the Year, Mathews is hoping to stick in the NBA after the Wizards, chocked full of bodies thanks to the Russell Westbrook trade, simply couldn’t spare the roster space to retain his services.

Mathews comes to Boston lauded not only for his shooting acumen but his work ethic. Scott Brooks, former Wizards head coach, lauded Mathews as “the poster boy” for playing hard. Brooks also recalled the story of Mathews’ pre-draft workout with the Wizards, where he left his impression by setting a record in their conditioning drill and running, as Brooks said, until “I thought his lungs were gonna explode.”

Last year, Mathews got to play in 64 games during the COVID-shortened season, a biproduct of both the increased trust in him from the organization and repeated injuries to the Wizards. From January 9th to February 3rd, Mathews was a mainstay in the rotation, averaging 11.2 points per game while shooting 41.7% from 3 on over five attempts a night.

In the first four games after he moved to a less prominent role, the Wizards were 1-3 and changed their rotation to get Mathews into the starting lineup. He started the next 21 games for Washington, playing fewer than 20 minutes a night but providing much-needed floor spacing next to Russell Westbrook, Bradley Beal and a spatially-challenged starting group. Volume wasn’t quite there for Garrison, but he shot a blistering 43.8% from deep.

In one of those starts, against the Minnesota Timberwolves, Mathews got going quickly. He’s lethal on broken plays and in transition, finding his way to the 3-point line and hunting extra passes to fire up a shot:

Think of Mathews in the Carsen Edwards role for a moment. The last few years in Boston, Edwards had been called upon as a floor spacer to come off the bench (or start) and get hot in a hurry. Little margin for error exists in those roles, and Edwards struggled, shooting 30.2% from deep across those two years. Mathews, meanwhile, is knocking on the door of 40%.

Edwards, supposed to be a strong movement shooter, went 4-24 combined off dribble handoffs and screens last year, according to Synergy. He was a poor spot-up threat (25% on catch-and-shoot looks) and didn’t fit the off-ball role Stevens needed next to Jayson Tatum and Jaylen Brown. Mathews went 22-of-48 (45.8%) on those same looks his first two years in the league. Folks, that’s an elite number.

Imagine Mathews fulfilling the movement shooter for Boston under Stevens and as a wrinkle out of the Celtics offense of the last few years:

Mathews struggled at times in Washington because of the ball dominance of both Westbrook and Beal. Placing Mathews as a pawn who stands in the corner isn’t the optimal usage of such a lethal movement threat. Last year, with both Beal and Westbrook in town, only 18.6% of Mathews’ attempts came from handoffs or screens. That number was closer to 30% his first year.

If such a warning sounds familiar to Celtics fans, that’s because it is. New head coach Ime Udoka will be tasked with integrating a great deal of new faces into a lineup built around Tatum and Brown while ensuring the playbook doesn’t devolve into “stand around and watch our young stars work.” By adding guys like Mathews, Josh Richardson and Aaron Nesmith over the last few years, Stevens and his crew are not-so-subtly mandating movement within the offense.

It’s important to understand the limitations Mathews brings to the table. Offensively, he’s going to be purely a jump shooter. Last year, only 12 of his 163 attempts (6.3%) in the half-court came at the rim, and four attempts were runners. He’d rather kick it out or take a step-back than face physicality or length at the hoop.

Defensively, Mathews’ Synergy statistics rate out poorly — often times not definitive proof of subpar defensive acumen but a confirmation of the eye test. With Mathews as the primary defender, his opponent shot 56.1% at the rim, and he was overall torn apart when having to guard the pick-and-roll. Two years in the league means the secret is out: when Mathews is in, make him guard in ball screens.

That shouldn’t be a major detractor to Mathews making the roster outright or sticking on a two-way deal. The offensive potency of dusting off a 15th man like this, who can come in and throw flames whenever the offense needs a lift, is more than most teams get from the end of their bench and the right piece to keep around. A “break glass in case of emergency” shooter has been popular as an end-of-bench threat, from guys like Matt Thomas to John Jenkins, Mathews to Armoni Brooks. Hell, it’s even how Duncan Robinson got his start.

Mathews will have to earn his way onto this roster. A spot won’t (and shouldn’t) be handed to him just because he’s coming off a good year. Every indication from his time with the Wizards, from his on-court production to the role he plays and every dollop of hard work in between, supports the case that earning a spot is easy money for Mathews.