The Celtics are built for the regular season (and the future)

The Celtics are built for the regular season (and the future)

Analytics

The Celtics are built for the regular season (and the future)

brad stevens celtics

Moving on from the remnants of the Ray AllenKevin GarnettPaul Pierce era by trading Jeff Green and Rajon Rondo during the season, the Boston Celtics weren’t expected to do much.

The Celtics’ record was 9-14 (39.1 win percent) before moving Rondo, and on January 15 at the time of the Green trade they were 13-24 (35.1 win percent). In return, the Celtics received two first-round picks and a second-rounder.

With a rookie coach and all of their top players gone, this was obviously the time to tank and get a high lottery pick, right?

Wrong.

The Celtics finished with a record of 40-42, winning 27 of their last 45 games, a 60.0 win percentage and a 50-win pace to finish the year. After the All-Star break, the Celtics went 20-11 and outscored opponents by 2.6 per 100 possessions, the ninth-best mark in the league.

The surprisingly strong finish shouldn’t have caught anyone paying close enough attention off-guard, however. After his ACL injury, Rondo was never a positive contributor on the court and the team always played better without him. Rondo finished the season ranking 65th among 79 point guards in ESPN’s Real Plus-Minus, and Green has throughout his career always been a negative for his teams. In fact, every single team he’s ever played on has been better with him off the court.

STATS

The storyline coming into this season was that the Celtics may have overperformed but would come back down to earth, in particular considering that the conference around them got better. The Heat got Chris Bosh back, the Pistons would get a full season with Andre Drummond and Reggie Jackson, and the Hornets traded for Nicolas Batum.

Now, the Celtics are sitting in the eighth spot in the Eastern Conference and have won 10 of their first 18 games. More importantly, they’ve outscored opponents by 3.9 points per 100 possessions, a mark fit for a high-forties win team. Once again, they’ve been solid, and they’ve proven again that they’ll be in the playoff hunt. However, there’s reason to expect them to be even better going forward.

While most expected them to fall back, the advanced analytics crowd was really high on them before the season, some going even as far as projecting them to win 50-plus games.

What was the rationale for such an optimistic outlook? After all, the Celtics  don’t have a single player you’d consider Top 10, or Top 20, or perhaps even Top 30 based on your evaluation of Isaiah Thomas.

The basic idea is pretty simple. When you look at the plus/minus column in the box score, you get a number based on how your team scored compared to your opponents with a particular player on the court. Obviously plus/minus doesn’t tell how well a player played in a game, after all you have teammates who did stuff and impacted the game in a positive or negative way that influenced your plus/minus. Adjusted plus-minus systems such as ESPN’s Real Plus-Minus are built to take into account who you played with, against, and it tries to separate a single player’s contribution to a team’s success.

Stephen Curry for example, was a +9.42 on a per 100 possession basis, while Raymond Felton was a -4.19. Every player in these systems projects as either a plus or a minus to their team’s success.

The Boston Celtics don’t have any +10 guys, but they do have a roster filled with “plus contributors”, which is crucial since most teams quickly run out of these “plus” guys quickly. The Mavericks for example had six last season, and even the shortest NBA rotation features at least eight players, with typically many more minutes to more players sprinkled in.

jared sullinger bos

Depending a bit on your calculation method, the Celtics were projected to have 9-11 players who were either “plus players”, or players who are very close to not being negatives. Not being negative being just as important as being a plus too. Ten of the Celtics’ current players had a RPM better than -0.5 last season, the highest number for any team in the NBA (including the Warriors).

Without a superstar, the Celtics are built on small and incremental “pluses”. Those small pluses add up, and the hypothesis is that together they add up to something pretty good, especially in the regular season.

Most superstars don’t play every game and their replacements in those games are terrible, and teams suffer injuries that are difficult to overcome in individual games. The Celtics are able to withstand players being out, as they are right now with Marcus Smart missing time with a knee injury. Just being able to sustain an average performance in every game over the gruelling NBA season gets you wins. Back-to-backs and four games in five nights are made easier when you can truly play “next man up” basketball and not suffer a significant drop-off at every position.

Brad Stevens is a big part of the Celtics expected success too. Few college coaches have been able to make the transition to the NBA, but Stevens has been brilliant. When you watch the Celtics, you’ll notice that the floor is spread and when players catch the ball on the perimeter they always make quick decisions – whether it be to pass, drive or shoot. What matters is that a player decides something, and doesn’t hold the ball and let the defense reset. The Celtics have the best inbound and end-of-quarter sets too. Most teams just run a simple high pick-and-roll to finish a quarter, but the Celtics more often than not have something cool up their sleeve.

FocusedWellmadeCopperhead

Celtics end of quarter play

The future looks bright in Boston, and with the treasure chest of the future draft picks they have (thanks be to Billy King and the Nets), they don’t even have to be bad to add to their already intriguing mix of talent – trades, or just getting the third pick in the 2016 draft from Brooklyn are ways for them to get a superstar level player or prospect.

Mika Honkasalo is an NBA writer, geek, chart maker and most of all fan. He studies computer science and works in software development and business analytics. His writing can be found at Nylon Calculus and Vantage Sports, and you can find him on Twitter @mhonkasalo.

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