Why we lost - Part I: Shooting in wins and losses

Why we lost is a series of posts that looks at statistical data and tries to analyze what the beyond-the-obvious factors for the Celtics' below average regular season performance were. The main goal is not to pinpoint what went wrong but to provide insight for potential improvements and material for always-fun "what if?" games.

It is easy to blame a loss on or give credit for a win to a certain referee/player/moment during a particular game: A wrong call, one clutch shot, one silly turnover, one big dunk, one dagger three... Opportunities are vast. Eye test or box score also serve that purpose well: A star player contributed with single digit points or a bench warmer put up double digit statistics? Mystery is solved. Your team committed half/double the usual amount of turnovers? Well, there you have it. However, the big picture also matters, and a comprehensive analysis of a team's tendencies in wins and losses can provide insight toward understanding why things turned out the way they did. In the first post of this series, I will look at how the Celtics did as a team and examine how acceptable it is to blame the usual suspects or whether there is more to what we know.

I: Shooting in General
Shot success comparison with league averages

It is not exactly rocket science to suggest that if a team shoots better, they are likelier to win a game. That's, unsurprisingly, also the case with the Celtics: In their 41 wins, they had a FG% of 48.8, shooting 38.4% from beyond the arc and 78.6% at the line. When they lost, though, their average split was 44 - 33.2 - 76.5. This amounts to shooting 2-pointers 9% worse and 3-pointers 14% worse. That easily explains why a "jump shooting team" would lose games. (For example, Indiana Pacers have managed to win 49 games in the regular season with a FG% average of 45.2. Memphis Grizzlies have shot 46% and 36.7% from beyond the arc, percentages right in between our winning and losing performances, to get 56 wins.)

An observation purely based on the shooting percentage therefore would not be more than stating the obvious. A look at how many shots the Celtics take per 36 minutes and per 100 possessions gives us a better idea on whether the Celtics' problem is just accuracy or there are other factors such as quantity and pace.

Per 36 min data reveals that the Celtics shoot the same number of shots on average whether it's a win or loss: 58.6 FG attempts in both cases while attempting 12.5 3-point shots in wins, 0.2 less attempts than in losses. Per 100 possession data doesn't paint a different picture: the Celtics actually take an insignificant amount of more shots in losses, yet when they don't fall, they lose.

II: Home and Away Performances

A team is expected to do better at home games overall: Crowd support, officiating bias, familiarity with the settings etc. all play a role in that. So by that logic one would expect a team to shoot better at home than away (if not the same) independent of the game result. Well, the stats reveal a quite interesting fact.

Our hypothesis holds for home wins vs. road wins (49-38.5 vs. 48.3-38.3 splits), yet the Celtics shot a horrendous average of 29.9% from beyond the arc in home losses compared to 34.7% in away losses. Free throw shooting data is even more mind-boggling: The Celtics shot 77.9% from the line in home wins vs. 80.1% in away wins, and when they lost at the Garden they manage to convert only 71.7% of their FTs whereas the away data for that is 79.1%. In other words, the Celtics free throw accuracy is significantly worse at home than away, even home wins have a worse average than away losses.

Sad KG is sad.
What does one make of it? Well, one explanation is that the Celtics are an emotional bunch, so if they're losing at home they cave in to pressure and fail to make FTs, and it becomes much harder for them to recover from a bad shooting night from the 3-point line. However, to understand this phenomenon better, one would have to look at individual player and game data. The following players performed significantly worse at the free throw line in home losses than in road losses: Avery Bradley (75% vs. 33.3%), Jordan Crawford (90.3% vs. 40%), Kevin Garnett (79.4% vs. 60.6%) and Paul Pierce (81% vs. 70.9%) The following posts will take a look at individual data more closely so I'll stop here, but these FT percentage drops are quite interesting.

III: Monthly, pre-All Star and post-All Star Averages

The shooting trend for the Celtics this season was quite interesting: They shot well in October (well, only one ame against the Heat) and November (52%-47.3%), then that percentage decreased to 44.5%, only to consistently improve month by month from then on. 3 pt shooting data is more interesting as it reveals a consistent slump until January when suddenly the team recovers from a 30.4% accuracy rate and wanders along 40% territory for the rest of the season. For some reason, Terry, Lee and Pierce all started converting a higher percentage of their 3pt attempts after the month of January passed. It is easy to connect this phenomenon with Rondo's absence, but without detailed analysis it would only be speculation.

I have previously -and unsurprisingly- concluded that the team's shooting percentages were significantly higher in wins than in losses, however a month by month breakdown of that data reveals that the Celtics became more dependent on 3PT% for wins after February, or post-All Star break. Before the All-Star break, the team converted 35.4% of their shots from downtown in wins vs. 32.3% in losses. OK. However, the post-All Star comparison of these two data is mind-blowing: 44.4% vs. 34.3% That's a huge difference. That comparison gains more meaning if when analyzed with the amount of 3pt shots taken per game: It increased from 16.8 pre-All Star to 18.0 post-All Star in wins and 16.3 to 18.6 in losses. Meanwhile, the number of FG attempts per game have decreased for the same period (80.5 to 78.4), which means that the Celtics started preferring 3 point shots over 2 point ones.

Seeing more of this won't hurt.
Why is that so? Well, it might be because the team finally got used to the absence of Ray Allen. It might be because a Rondo-less team actually found more opportunities for 3pt shots. It might be that Terry and Pierce finally gained confidence/got in shape. It might be that Doc realized that jacking up more shots from downtown meant more points even if the team would convert less, and since the Celtics shoot a lot from mid-range, it wouldn't mean a drastic change for the team's style of play.

Did it work? Well, to some extent, as I have explained above. Taking more 3 point shots won't hurt, but wins and losses cannot be solely associated with that. Yet that's definitely something the Celtics should consider, especially given the current state of the league.

IV: Team Shots per Distance

The Celtics shot worse in losses, but another related question would be whether it made a difference from where they shot. Apparently, it did.

We can split the shots the Celtics took into 6 categories and look at difference in which categories stand out more.

         Within 5 feet -- 5-9 ft -- 10-14 ft -- 15-19 ft -- 20-24 ft -- 25-29 ft (beyond the arc)
W           59.1%       40.7%     51.8%      46.2%       41.2%     38.3%
L            56.0%       36.9%     38.0%      41.0%       40.3%      30.0%

It is not that difficult to find the culprit: If our mid-range shots, i.e. shots from 10-19 ft don't fall, we lose. Especially the drop in 10-14 ft category is amazing. Well, that shows one thing: Tommy Heinsohn is right to become infuriated when the team doesn't attack the basket and settle for such shots when we're losing.

V: Conclusion

Even though the results in this post aren't that surprising, there are a few gems: The weird FT% in home losses, the increased accuracy of shots post-All Star break and the conditional/occasional need to distance ourselves from the mid-range shot. Rondo's absence in the second half also made this team opt for more 3pt shots and convert a higher percentage, and I'm sure there are some lessons to be learned in the videotapes.