I saw a thread in r/Leafs in reddit which raised a question and piqued my interest:

Is Matthews still dealing with his shoulder?

I often have wondered how long a player like Auston needs to fully recover from a shoulder injury. This may be because I myself suffered a shoulder injury which set me back for months. (They’re painful too!) Last season many fans theorized that Auston’s lack of goals was related to his recent shoulder injury (the one where Cal Clutterbuck and friend sandwiched him in open ice).

Although Matthews went on IR for a shoulder suffered back in late October at the hands of Jacob Trouba, the reddit thread centres around the Niklas Kronwall hit back on December 6 when Auston was checked shoulder first into the corner boards.

Just for reference, I think this is the last goal Auston scored before that hit, back on December 4th. It was an OT winner against Buffalo and the snap had snappity zing.

Many have noticed that his scoring has dropped off in the 11 games since the Red Wings game on December 6, even though Auston missed no time. And this has led to the question raised on r/Leafs.

My approach will be to focus on his shooting percentage and shot locations before and after December 6th. It may not answer every question we may have but if it is a shoulder problem, it should be reflected in his ability to shoot the puck.

Before we dig in, I should also remind us all that Auston was due for a regression in shooting percentage given his historical shooting rates and the blistering goal-a-game start he had in October. He had been on fire as well after his return November 28th from a month-long IR.

Let’s take a look at the shooting percentages over Auston’s career — it has been growing each season and has always been above average. It’s up again this year and the split before and after Dec 6 is dramatic, dropping down to 11.4% from 30.6%.

All Strengths:

2016–17: 14.44%

2017–18: 18.18% (3 injuries)

2018–19: 22.35% (30.6% before Dec 6, 11.4% after)

Powerplays offer unique shooting opportunities and PP time can vary, so let’s take a look at his 5v5 play. The 5v5 shooting percentage is roughly the same since the start of last season and the before/after splits this season are about the same as well.

5 on 5:

2016–17: 13.49%

2017–18: 18.57%

2018–19: 18.18% (18.92% before Dec 6, 16.67% after)

Now let’s move to the Powerplay. There’s definitely a signal here. Auston has been getting PP1 time this season and that added a big boost in October as many of us recall. The setups from Marner led to quick snaps into the net. The PP has cooled right off both for the PP1 unit and Auston, and so far I would think it has more to do with the Leafs trying to adjust as other teams focus more on Matthews and Marner. Clearly this is where his shooting results have dropped off — from an insane 75% down to 7.69%.

Powerplay:

2016–17: 20.0%

2017–18: 16.67%

2018–19: 31.82% (75.0% before Dec 6, 7.69% after)

Below is the shot map for the 14 games before December 6 (all strengths). Has anything changed as far as chances and locations? Lots of red dots, those are goals coming from both the inner slot dangerous area and further out in the left circle. The MoneyPuck xG model would have predicted 7.57 goals from this shot map, Auston doubled that by scoring 15 goals on an unsustainable 30.6% shooting percentage.

14 games prior to December 6

The shot map below covers the 11 games after December 6th. Those goals dried up and the shooting percentage dropped below Auston’s normal rate, down to 11.4%. As I showed above, this drop is driven by the Powerplay. But you can see here the shot volume per game and pattern is more or less the same.

The average shot distance is slightly further out but not significantly so. The model used for this shot map predicted an average player would score about 4.1 goals from these locations and Auston did in fact score 4. In other words, he was average which would be below average for him given his shooting talent. If he had scored an extra goal or two, that would have been more his average. But players can’t score goals according to some average, they will fluctuate game to game and that’s probably all we’re seeing here.

11 games post December 6

So if Auston does have a lingering shoulder injury that affects his shooting, it’s not obvious in the numbers. In fact, the more likely theory is that his Powerplay shot success is drying up — the heady days of early October are gone and opponents have adjusted to that Leafs Powerplay strategy.

Let’s look at a few of Auston’s shots since December 6th to wrap things up.

I’ll start with this scrum in the crease. His strength seems to be fine and he’s not too shy.

This shot just before Christmas wasn’t a goal but it seemed to have mustard and beat the goalie far side.

Auston was wide open here, easy goal. That Marner kid. Geez.

This shot on December 20th has AM34™ stamped all over the puck. I don’t see anything wrong with his skill or shoulder strength here although you could argue it was unusual in the way he kneeled down and the way he got it away. But it appeared to have more to do with where he had to receive the puck and his ability to adjust his shot was pretty remarkable given the situation.

If he’s still recovering from injury, it’s in the margins because he can still shoot and the 5v5 numbers don’t have a story to back it up. I’m the last one to think that a shoulder injury is 100% better after one month but there is no solid evidence that I can find that Kronwall’s hit reduced Matthews’ performance.

A regression in his shooting percentage was to be expected especially with his early PowerPlay results and that explains most of his drop-off in goal production.

I don’t think we can underestimate how important those Powerplay pre-shot cross-slot passes were back then. Matthews was bagging a goal on almost every shot. It was a combination of his shooting skill, loose PK coverage early in the season, and the inability of the goalie to re-adjust after those crisp cross-ice passes.

If we had seen a trend where Auston’s 5v5 shooting percentage dropped off a cliff, then maybe the injury theory would hold more water. But we didn’t.

Shooting percentage is notorious for going up and down during a season and has been known to drive normally sane fans, writers and radio pundits to great lengths in quest of the answer to the eternal question “why?”.

The fact is, goals are a privilege and not a right. The puck decides if it wants to go in the net sometimes because it’s driven by many largely random forces. Goals are rare. Counting them up for one player over a small season segment is a mug’s game. Just ask Marner, Kadri or Nylander.

Usually when I write something like this, the hockey gods send the player on a streak. Let’s hope.

Credit to several hockey data sources used in this article — NaturalStatTrick.com, corsica.hockey, offsidereview.com, MoneyPuck.com