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Numbers Game: What is Wrong with the Defense?

Something’s certainly wrong. But how do the Raptors fix it?

NBA: Toronto Raptors at Los Angeles Clippers Gary A. Vasquez-USA TODAY Sports

The Raptors have started the year in much the same way as last season. After 14 games, they are 8-6 (as they were last year) and a top team offensively (3rd in ORTG this season, 6th last year at this point). Valanciunas and Carroll have both missed a few games, just like last season.

One big difference though, is the defence. Last season the Raptors were ranked middle of the pack in DRTG at this point in the season (13th, 100.2 DRTG). This season, 22nd, with a 106.1 DRTG. Last season they eventually worked their way up to 11th, but they’ll need more than a 2 spot jump from where they stand now to have a passable defence come the playoffs.

Before we continue, here is your weekly reminder that we have yet to even play 20 games yet, so there are small samples aplenty in what is to follow, though I do my best not to use anything with a completely unreliable sample.

So, what has gone wrong?

Biyombo is Gone

Well, there’s that. Last season, Biyombo posted an on-court DRTG of 100.6, anchoring the defence for the bench. You’d think that’s the difference - no more Biyombo, no more defensively capable bench units, with less experienced and impactful players backing up the centre spot.

Easy answer. Wrong, but easy.

Lucas Nogueira has thus far posted an on-court DRTG of 101.2 as the backup centre. Jakob Poeltl, in the few minutes he’s played, as posted an on-court DRTG of 104.7 (better than the team’s overall defensive number). They are not the problem, and neither is the bench. The bench continues to post solid defensive numbers (though not quite as solid as last year) with Patterson and Ross also posting decent on-court defensive ratings in the 104 range. I mean, look at Cory Joseph, who had the best on-court DRTG last season (100.2) in spite of playing long stretches in closing lineups against opposing starters. He’s putting up a... wait, what?

Joseph so far this year has posted a team-worst 110.4 on-court defensive rating. Huh?

Is Cory Joseph Broken?

Cory Joseph, the most consistent defender on the team last season, appears to be tanking the team’s defensive rating whenever he touches the court. This makes little sense at first glance.

He has certainly struggled this year, on both ends of the floor. But to swing from one of the best defensive difference makers on the team to seemingly the worst is pretty extreme.

Worse yet, it is very hard to pin down why the team struggles with him on the court. His individual defensive numbers are very good. He’s not leaving guys open for spot up shots - he is forcing opponents shooting spot up shots to a 22% FG% and 33% eFG%. Teams are going at him in the pick and roll - over 55% of his possessions defended have ended as the primary defender on the ball handler in a screen play (far more than anyone else on the team - Lowry next closest at 42%). But he’s stopping them, forcing only 0.8 points per possession and a turnover rate close to 30%. He’s not being taken advantage of as an isolation defender - he’s only been isolated on 6 times this season!

So, Joseph is doing everything well individually, and yet the team is a disaster with him on the court. Let’s take a look at his top used lineups and see if there are any patterns we can spot.


Those are all the lineups Joseph has played at least 20 minutes with. It’s good to see that Lowry-Joseph lineup still works like a charm, though better with Nogueira than Poeltl, which makes sense with BeBe being more similar stylistically to Biyombo (and having the benefit of not being a rookie). Even the Poeltl lineup though is better than Joseph’s on-court rating.

That third lineup might be the key here. Same lineup as the Lowry-Joseph bench unit except with DeRozan instead of Lowry, and the defence falls off a cliff. Joseph has worse defensive lineups with much smaller samples (that Nogueira and Valanciunas both make appearances in), but this lineup, with the very bad defensive rating and decent sample size, is a big contributor.

So, what’s the problem? Is Nogueira that much of a downgrade from Biyombo defensively? His overall defensive rating suggests he is not, as does his apparent fit with the Lowry bench unit. Last season, the same DeRozan-plus-bench unit with Biyombo in Nogueira’s place played over 200 minutes and posted a stellar 91.0 DRTG, by far the best defensive lineup on the team (with more than 80 minutes played).

Looking at all of Nogueira’s metrics, he seems to be performing as a perfectly acceptable defensive substitute for Biyombo. His on-court DRTG as noted above is very similar to Bismack’s. His defensive BPM is +5.9 so far (a crazy number that will almost certainly shrink with time) to Biyombo’s +2.3 last season. For the record, last season Nogueira posted a +2.9 in over 200 minutes played, so he really is shaping up like a very solid defender. Biyombo’s block rate of 6% last season is dwarfed by Nogueira’s 8% this season. And while Biyombo far outshines Nogueira on the glass (~30% total rebound rate versus ~20%), that problematic lineup for Joseph posts a perfectly respectable 74% defensive rebound rate.

What’s the Problem, Then?

Let’s look back at some of the on-court and off-court defensive ratings for the team.

The worst on-court defensive ratings on the team:
Cory Joseph 110.4
Norman Powell 108.4
Jonas Valanciunas 108.0
DeMar DeRozan 107.4
Pascal Siakam 107.1

The best off-court defensive ratings on the team:
Demar DeRozam 101.7
Cory Joseph 103.1
Jonas Valanciunas 104.0
Norman Powell 105.2
Pascal Siakam 105.5

The worst on-off differences for those 5 players:
Cory Joseph -7.3
DeMar DeRozan -5.7
Jonas Valanciunas -4.0
Norman Powell -3.2
Pascal Siakam -1.6

So, the common refrain of Valanciunas being a problem may have a point - though having an offensive player sub off for a defensive one will always generate at least some drop off in defence. And his off-court DRTG is still above the overall team rating last season, and not too far below the overall rating this year. Still, add him to the list of suspects.

And you’ve got a couple young, relatively inexperienced guys in there who have been placed in very demanding roles - Siakam with the starting unit, and Powell with the closing unit on many nights. So some issues are to be expected there, and at least some small portion of the team’s struggles defensively might stem from playing young players more than last season, but neither of them are that close to the top of the list above, so we’ll leave them alone for now.

But the biggest name to pop out here (and the player on this list with the most minutes played and therefore the most influence over the team as a whole) is Demar DeRozan. His -5.7 point swing is second worst on the team to Joseph, and his appearance in that struggling bench unit seems to be the only difference between that lineup and the one that is finding so much success defensively.

So let’s quickly take a glance at some impact numbers (metrics like BPM that try to isolate the impact of an individual player on their team) to see if there are any clues to who is the biggest culprit, or if there are several.

Cory Joseph | -0.8 DBPM | -2.1 DRPM
DeMar DeRozan | -2.4 DBPM | -1.6 DRPM
Jonas Valanciunas | -0.9 DBPM | +0.8 DRPM

Joseph is certainly looking to struggle, but these numbers paint DeMar DeRozan as the biggest culprit on the team, or at the very least among them.

And this is not an attack by any stretch. DeRozan has carried the team offensively in the early going, as evidenced by his team-best +4.3 offensive BPM, and is carrying an insane load, at 36% usage (his previous career high being about 30%) and 37 minutes per game. In the history of the NBA, there have only been 14 player seasons (by 10 total players, including DeRozan right now) where a player has posted 36 MPG and 35% usage, the most recent of which is Carmelo Anthony in 2012-13. That’s the sort of thing that would make any player take it easy on the other end, and maybe there’s a good reason we haven’t seen a player hit those benchmarks in nearly half a decade.

Maybe the problem is not completely with the defence (though I’m sure the coaching staff will be trying some things to tighten it up regardless). A player carrying a load like DeRozan is carrying is almost unprecedented - there’s a reason no one since Michael Jordan managed an early season stretch like DeRozan has had on the offensive end this year. It’s exhausting. Near impossible for even the most talented of players - but also just a huge energy drain on a player.

Perhaps part of the problem, and part of the solution, could lie in the offence instead. The team is scoring at an incredible rate, but at the same time breaking the back of one of it’s heaviest minute contributors with an offensive load rarely seen in the modern NBA. It’s worth reminding ourselves of the success the team had on the offensive end last season, with DeRozan carrying less than 30% usage for the season. This team can score in many ways, but right now they are scoring primarily in one way, and it may well be contributing to the early season defensive struggles of one of the team’s star players.

There are various other things that can help with that - Joseph for example showing he can carry some offence with that bench lineup would mean less of a load for DeRozan, as, hopefully, should the recent improved shooting from the supporting cast. The team is getting back cut to death (giving up the 2nd most cuts in the league, at 1.29 points per cut, is never going to help a defence), and the team needs to sharpen up in that area, as well - and tired guards seem more likely to lose focus and lose their man on the weak side. There are many other smaller issues that can’t be covered in one piece, as well.

In any case, we’ll keep an eye on how the offence shifts as the season wears on, and whether perhaps we see some improvement from the team defensively as the load gets shared around more (if it does).

Lineup, play type and on-off court data from
BPM and rate stats from
RPM from