Four stats that loom large over the Toronto Raptors and Boston Celtics ahead of their second round series

The matchup we've all been waiting for is here.

After both teams took care of business in the first round by way of sweeps, the Toronto Raptors and Boston Celtics will face off against each other in the second round of the playoffs for the first time in NBA history.

The Raptors and Celtics have been pretty evenly matched all season long. We're talking about two of the better teams in the Eastern Conference, both of whom are incredibly well-coached, feature two rising stars who play both ends of the court and have the firepower to make it all the way to the NBA Finals this season.

So what are the keys to victory? Here are four stats from the regular season that could play a role in which team comes out on top.

40.4: Jayson Tatum's shooting percentage on pull-up 3s

Tatum proved to be one of the best 3-point shooters off the dribble this season.

According to NBA.com, Tatum was one of only nine players to make more than 100 pull-up 3s during the regular season, the others being James Harden, Damian Lillard, Trae Young, Luka Doncic, Devonte' Graham, Kemba Walker, Buddy Hield and Zach LaVine.

Of those players, Lillard was the only one who could match Tatum in the efficiency department.

Tatum becoming one of the league's most prolific 3-point shooters off the dribble has played a tremendous role in his breakout season. While he's more than capable of playing without the ball in his hands, he has upped the frequency with which he's scoring as the ball handler in pick-and-rolls and isolation each season he's been in the league. According to NBA.com, Tatum has gone from generating 22.9 percent of his offence on those plays as a rookie to 27.8 percent as a sophomore to 41.3 percent this season.

Being able to consistently make shots like this...

...has turned him into a new player because he's now a legitimate three-level scorer. Tatum isn't as reliant on midrange pull-ups as he was last season, but he's proven that he's comfortable scoring from that in-between range. And in making a more concerted effort to attack the basket, he's getting to the free-throw line more than he ever has before.

The result? Tatum is one of the toughest matchups in the league, someone who is capable of going for 30-plus points on any given night.

It goes without saying, but the Raptors will have their hands full trying to slow the All-Star down.

28.5: How many points per game Boston's bench averaged

It was the second-lowest rate in the league. The only team with a lower scoring second unit than the Celtics was the Portland Trail Blazers with 26.6 points per game.

The Raptors were only a few spots ahead of the Celtics and Blazers, but a lot of that had to do with the injuries Toronto dealt with, as it forced the likes of Serge Ibaka and Norman Powell to start in more games than they were expected to coming into the season.

Boston's second unit is even thinner now that Marcus Smart has been moved into the starting lineup to replace Gordon Hayward, who recently left the NBA Campus in Orlando to return home with a sprained ankle. After Smart (12.9), Enes Kanter was the team's leading scorer off the bench during the regular season with 8.1 points per game. Following him: Brad Wanamaker with 6.9 points per game and Robert Williams with 5.2 points per game.

They're each capable of making an impact, but they will have a huge target on their backs whenever they take the floor in this series — Kanter because of his perimeter defence, Wanamaker because he's not much of a playmaker, Williams because he's inexperienced and a fouling machine.

With how evenly matched the Raptors and Celtics are in other categories, which team can get better production from their bench could help swing the series. The Raptors have the clear edge entering Game 1, although the severity of Kyle Lowry's injury could test their own depth.

21.6: The frequency with which the Raptors scored in transition

In other words, the Raptors scored more than a fifth of their points in transition in the regular season, the highest rate in the league.

Lowry and Pascal Siakam led the charge with 5.8 points per game each in the open court, trailing only Giannis Antetokounmpo (8.3), Russell Westbrook (7.4), James Harden (6.8) and Bradley Beal (5.9) for most in the league. Powell and Fred VanVleet weren't far behind with 5.1 and 5.0 points per game in transition, respectively.

The reason that's noteworthy is the Celtics were one of the most effective teams at keeping teams out of transition. They gave up only 17.7 points per game in transition and ranked in the 69th percentile in allowing only 1.08 points per possession.

It played a role in the Celtics giving the Raptors trouble in the regular season. As NBA.com's John Schuhmann noted, Toronto's "four regular-season meetings with the Celtics account for four of the 19 times that the champs were held to 13 fast-break points or fewer."

Personally, I think this could be the biggest factor in the series. The Celtics score a decent amount of their own offence in transition and the Raptors actually had the most effective transition defence this season, but I trust Boston's halfcourt offence far more than Toronto's. The stats back it up. According to Cleaning The Glass, the Celtics ranked 11th in halfcourt efficiency this season compared to 17th for the Raptors.

If the game slows down, the numbers point to it favouring the Celtics more than the Raptors.

82.8: Gordon Hayward's versatility rating on defence this season

According to data collected by Krishna Narsu of The Bball Index, Hayward was the most versatile defender in Boston's starting lineup this season.

Not by much — Tatum's versatility rating was 80.0 and Brown's was 82.2 — but Hayward took on a lot of different matchups for the Celtics, spending an estimated 21.9 percent of his minutes guarding point guards, 26.8 percent guarding shooting guards, 24.4 percent guarding small forwards and 18.5 percent guarding power forwards.

Now, just because a player is capable of guarding multiple positions doesn't necessarily mean they're good at defending multiple positions, but Hayward has proven to be a solid perimeter defender who has the size and length to give smaller players trouble. He fits in well with the Celtics in that regard because he gives them the flexibility of switching almost across the board when Tatum and Brown are also on the court.

Without Hayward, the Celtics have turned to Smart, who is a far more accomplished defender, albeit one who doesn't have quite as much size. I'm interested to see what sort of impact that has against the Raptors considering they have one of the smallest starting backcourts in the league with Lowry and VanVleet. 

If nothing else, it will force the Celtics to match-up with the Raptors differently, as Hayward's primary assignment in the regular season was OG Anunoby. I wouldn't be surprised if Walker starts the series on Anunoby, leaving Smart, Brown and Tatum to matchup with Lowry, VanVleet and Siakam — assuming, of course, that Lowry is good to go for Game 1. In which case, expect to see some more of Anunoby in the post.

The Celtics will miss Hayward even more on offence in this series. He was their fourth-leading scorer on the season with 17.5 points per game and ranked third on the team with 4.1 assists per game. He gave them another shooter, another creator off the dribble and another passer. With him on the court, Boston's offence improved by 4.0 points per 100 possessions in the regular season, representing one of the biggest margins on the team.

Hayward hasn't been officially ruled out for the series, but the expectation is that he'll miss another three weeks, making a return anytime soon highly unlikely.

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