ZARDES RISING: Genuine Growth or Stat Inflation?

The star of Gyasi Zardes is rising, and it’s rising fast. Coming off a season which was by all accounts terrible for a player who was billed as a goal scorer, Gyasi has managed to turn things around in 2014 and is currently the top scoring American in the league. Last year, Gyasi scored 4 goals in 78 shots. This year, he’s scored 15 goals in 57 shots, as of September 13th. The change from last season to this season has been staggering.

Just take a look at the following player radars put together by Alex Olshanksy. The first is from the 2013 season, the second is 2014.

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You don’t need to know much about statistics to spot the difference: in 2014, Gyasi is putting the ball in the back of the net.

But in the case of any young player, it’s important to remember that statistical improvement and growth are not always the same thing — and that’s especially true when it’s comes to strikers. So what exactly is behind Gyasi’s success this season?

Over the course of the last couple of months, I have been delving deep into the stats to determine exactly that. During this same time, I have also studied Gyasi as a person—his personality, work ethic, and the goals he has set for himself this season.

What I found was a story of tremendous nuance. Gyasi Zardes is putting up incredible numbers. Last year he wasn’t. Are we witnessing the growth of a star, or is this a case of statistical inflation?

To answer this properly, we have to do some digging.

 

“Last year” Zardes tells me, “I was always trying to score the beautiful goal — upper 90.”

For Galaxy followers, this explains a lot. Amongst fans, Gyasi’s errant shots in 2013 had become a bit of a running joke. One night early on in the season, Gyasi showed up at a Galaxy II game to support the lower division team. After the game was over and as he was walking out to his car, a fan called out to him.

“Gyasi!

Gyasi turned around to see who was calling.

“Shots on goal, Gyasi. Shots on goal.”

Gyasi grinned widely and waved. Looking back, I don’t think he was simply being polite. I didn’t recognize it at the time, but Gyasi’s smile was almost a humble gesture of accountability. A recognition of the problem. A promise to get better.

Oftentimes young talent have a swagger and bravado that gets in the way of their development. Now, I’m not about to claim that Gyasi Zardes lacks swagger — I don’t think you can level that accusation at anybody rocking a bleached mohawk. But with Gyasi there’s something refreshing about the swagger.

On one hand, there is confidence, but on the other hand, there is a humbleness — and it’s the latter which separates Gyasi from many young stars. Amidst his goal scoring streak, one journalist asked him after the game how satisfying it was to score. “As far as satisfaction, I’m not satisfied,” replied Gyasi, “Because I haven’t achieved nothing. You know, I’m just going to keep working hard, and keep learning from my teammates.”

When it comes to mentors, Gyasi has learned a lot from Robbie Keane. “I’ve definitely been listening to Robbie. He’s CONSTANTLY talking to me,” Gyasi tells the media after the San Jose game.

One instance in particular stands out. At the early stages of Gyasi’s midsummer streak, Robbie Keane recounted an incident to Kyle Martino. Gyasi was watching a lot of Cristiano Ronaldo videos of step-overs and other flashy aspects of the game, and Robbie pulled him aside and told him to stop watching that stuff. According to Martino, who would later tell the story on air, Keane told Zardes: “You need to think about just one and two touches in the box, and your bread and butter — scoring goals.”

But it would be unfair to paint Gyasi as a mere bystander in his growth, patiently waiting for revelations like this to be sprung upon him. The fact of the matter is, Gyasi Zardes is a sponge — actively absorbing everything he can about the game. “I love watching [Robbie] practice” he told Kelly Tennant after a game against Chivas USA.

Perhaps part of the reason that Gyasi has been so successful is his student mentality. You can hear this in a number of his quotes to the media: “You know, all of these guys are great players, and I can learn something from each and every one of them.”

Just take a look at what Gyasi’s said about what he’s learned from Landon Donovan: “Just being smart on the ball, you know. He’s a guy with pace, with speed, but he utilizes speed by knowing where he is going to run, when he’s going to make that run … You know, I’m trying to take that from him, as opposed to me just running all over the place … Just choosing my time and my position to run, you know?”

And then there’s the work Gyasi puts in.

“At the beginning of this year, I really put the effort into just putting the ball on frame, and PRACTICE” he says to me, putting extra emphasis on the word, “putting the ball on frame.” His emphasis was striking, almost as if it was for his own benefit rather than mine. A mantra of sorts he’s been drilling in.

That’s a good narrative – and a human one – but it’s not the whole story.

 

Gyasi’s focus in 2014 has been all about shot selection and placement. In 2013 Zardes was taking a ridiculous amount of shots, and he wasn’t putting very many of them on frame.

gyasi linechart

This year, however, he’s taking far fewer shots, and putting far more on goal:

2013 2014
Shots per 90 3.2350 2.8723
SoG per 90 0.9539 1.3101
Shots on goal % 29.487 45.614

*As of 9/12/2014.

These sort of stats are easy to grok – shots on goal isn’t exactly a complex idea – but they’re also rather surface-level. To better evaluate Gyasi, I reached out to the good people at American Soccer Analysis, and they graciously provided me with in-depth shot data.

American Soccer Analysis is a wonderful site that does a lot of calculations, mostly having to do with a metric known as Expected Goals, or ExpG. Expected Goals is a stat that I will explain in more detail a bit later. For now just know that in order to calculate this stat, they split the field into the following 6 zones:

ShotZones

Using American Soccer Analysis’ data, I have put together the following table to demonstrate which areas of the field Gyasi’s numbers have improved the most. Again, this should not be construed as the areas where Gyasi has improved the most – only his numbers. In order to judge growth, we will have to delve even deeper.

SOG 2013 SOG 2014 % +/- Conversion 2013 Conversion 2014 % +/-
Area 1 0-3 0% 2/6 33.33% +33.33% 0-0 0% 2/6 33.33% +33.33%
Area 2 9-30 30% 11/27 40.74% +10.74% 3/10 10% 7/27 25.93% +15.93
Area 3 7-28 25% 6/10 60% +35% 1/28 3.57% 3/10 30% +26.43
Area 4 4-7 57.14% 6-11 54.55% -2.59% 0/7 0% 3/11 27.27% +27.27
Area 5 3-9 33.33% -3 0% -33.33% 0-9 0% 0-2 0% 0%

On the surface, the data backs up the growth narrative. One of the biggest areas of improvement has been in zone 3. Gyasi is taking about 3 times fewer shots in the area, but the shots are finding frame at nearly 3 times the rate. As of 9/12/14, wholly 20% of Gyasi’s goals have come from here.

The numbers seem to suggest that the hours Gyasi spent practicing putting the ball on frame have paid off. If you take away blocked shots (as it is impossible to know whether they were heading on frame or not) the data shows that Gyasi is missing the frame a lot less in zone 3, and missing the frame a lot less in general.

Shots2013 Shots2014 Miss2013 Miss2014 Miss % 2013 Miss %2014
Area 1 3 6 3 4 100% 67% -33%
Area 2 30 27 14 10 47% 37% -10%
Area 3 28 10 11 1 39% 10% -29%
Area 4 7 11 0 2 0% 18% +18%
Area 5 9 3 4 2 44% %67 +23%

According to Gyasi, putting the ball on specific parts of the frame has also been key. “I’m really just putting it low, and putting it wide — so the keeper don’t touch it, and it’s going in,” he tells me.

The very next day in a game against Chivas USA, Gyasi scored by deftly placing the ball low and wide — exactly where he told me he’s been working on putting it all year:

Far from an isolated incident, scoring goals in the corners is something that Gyasi has been doing throughout the season. As of September 12th over half of Gyasi’s goals have been low and in the corners.

Total goals 2014

This year Gyasi has scored a combined 6 goals from zones 3 and 4. Last year that total was one — despite taking 13 more shots. And looking at where those goals are being scored, one can’t help but draw conclusions.

z3

z4

So, has shot placement been the key to Gyasi’s incredible turnaround? Unfortunately, the data paints a picture that’s not quite so neat. Here are all of Gyasi’s shots on goal this year, as of September 12th:

Shot accuracy 2014

And here is the same chart for last year:

shots 2013

Now our narrative has a new problem. While Gyasi has improved in terms of keeping his shots down and on frame, his shots on goal have always been clustered in the corners.

So why is he scoring so much more this year?

To fully address this, first we must debunk the notion that “finishing” is a skill that bears any significant weight in judging a striker.

Statisticians don’t put much weight into a player’s goal conversion numbers. The ideal metric is the one muddied by the fewest variables, and, for predictive purposes, the one that has a history of repeatability. Conversion rate fails in both categories. Its main problem is that it weighs all shots equally, when – as any soccer player will tell you – this is far from the reality of the game. Certain shots are harder to convert than others.

For this reason many analysts rely on that magic metric I mentioned earlier: Expected Goals. For a good laymen’s primer, I highly recommend this article. Getting Expected Goals is a process. First, take a number of data points – like shot location, type, and whether or not a shot was assisted – to determine the likelihood of a player scoring from a shot, as determined by league average. This is referred to as shot leverage. Then multiply a player’s total shots with their average shot leverage and you’ve got a player’s Expected Goals.

A stat that often accompanies expected goals is G-xG — how many goals a player is either above or below their expected goals mark. According to American Soccer Analysis, last year Gyasi fell nearly 4 goals under what an average player would be expected to score given similar opportunities. This year, however, Gyasi is outperforming his expected goals by a whopping 7.16 goals, as of September 12th. That’s best in the league.

So has Gyasi’s finishing improved? Is this the pay-off of all that practice?

It’s an intuitive assumption, but the nature of G-xG is counter intuitive. Its main problem is simply repeatability. In a thought provoking 11 tegen 11 piece, this point is pretty convincingly demonstrated. Since a player’s expected goals tally is dependably repeatable, while his G-xG is not, the article concludes that strikers should be judged more on their underlying expected goals, and not on how many goals above or below this mark they are.

So finishing, even when viewed through the lens of G-xG, is a product of so many factors that it’s almost totally irrelevant in measuring a player’s growth. The best explanation of this comes from Harrison Crow of American Soccer Analysis:

“It’s not that finishing ability isn’t really a skill… however, at the level of which Zardes plays it’s so standardized that the difference between players that are perceived bad at it and players that are perceived good is a lot less than what most would believe.”

So, which type of striker is Gyasi Zardes? A striker that relies on the unreliable, outperforming his expected goals, or a striker who gets himself into enough goal scoring chances that his numbers can be counted on from year to year?

 

That’s where the statistical nuance comes in. While Gyasi has improved in terms of taking better shots, the data yields numerous warning signs that what we are dealing with is far more a case of statistical inflation than it is about actual growth.

A huge component of the Expected Goals formula is the number of chances a team generates for the striker. Despite LA’s high-flying attack, an offense that leads the league in big chances created, Gyasi is 15th in expected goals. This is an extremely surprising stat which suggests that Gyasi’s positioning isn’t giving his teammates that many opportunities to feed him chances on goal.

Evidence for this can be found in multiple stats, especially when comparing Gyasi to the players surrounding him in the golden boot race:

Players Goals Attempts Shot Leverage Expected goals G – xG
Bradley Wright-Phillips 21 84 0.182 15.29 +5.71
Dom Dwyer 18 91 0.153 13.88 +4.12
Gyasi Zardes 15 57 0.138 7.84 +7.16
Robbie Keane 14 104 0.124 12.90 +1.10
Erick Torres 14 78 0.158 12.36 +1.64

*As of 9/12/2014.

Zardes’ Expected Goals number the clear outlier amongst the strikers in the Golden Boot race. The primary reason for this is that he isn’t shooting very often. Remember: expected goals is calculated by multiplying total shots by shot leverage. Since Gyasi’s shot total is equally anomalous, it is clearly the primary factor in his low ExpG number, and thus his league-leading G-xG total.

So why is Gyasi outperforming his shot total? A big clue can be found in comparatively low percentage of his shots which are unassisted.

Players Goals Unassisted shots G – xG
Bradley Wright-Phillips 21 14.3%. +5.71
Dom Dwyer 18 24.2%. +4.12
Gyasi Zardes 15 7% +7.16
Robbie Keane 14 17.3% +1.10
Erick Torres 14 30.8% +1.64

Both a striker’s ability to get into dangerous situations and his teammates’ ability to feed him the ball in those situations are a part of the makeup of the expected goals metric. It is entirely possible that Gyasi’s Expected Goals number is so low because he is simply not getting into dangerous situations enough, as can be seen in his low shot total — but when he does, the impeccable service of Donovan and Keane is putting him in great positions to score.

In other words, Gyasi isn’t holding up his half of the stat nearly as well as the other strikers on the list, but the quality of the service he’s getting is simply that much better.

The data suggests that Gyasi Zardes, unlike Robbie Keane, is relying primarily on the service of others to score his goals. Listening to Zardes, this doesn’t seem to be lost on him.

After the New England game, Scott French asked him if he was surprised by the way things were going. “I’m not surprised,” replied Gyasi, “because my teammates are doing all the work and just playing me in.”

Gyasi isn’t creating very many goal scoring opportunities for himself — instead he’s excelled at converting a very high percentage of his shots. As I explained earlier, however, there is very little correlation year-to-year between G-Gx. It would be a mistake to expect Gyasi to continue to score at these rates in the future.

 

Does this mean that the homespun narrative of the humble student, growing under the guidance of his elders was just a load of bunk?

Not entirely. Obviously Gyasi’s stats are being inflated — but I think it would be a mistake to discount his growth entirely. His focus in training – on putting shots on goal – though not the most reliable metric in terms of repeatability, is showing itself in the stats. I think the sizeable decrease in misses from zone 3 bolsters the case that the dramatic increase in shots on goal from that same area is not only a matter of assisted vs. unassisted shots, as there has been no real change in the percentage of shots being blocked. I also think that his efforts in training have bore fruit in that he is skying fewer shots over the goal.

As someone who loves his work ethic and humble character, I can’t help but see a tremendous amount of promise in this kid who is willing to recognize his faults and work so tenaciously to improve them. Speed, size, athletic ability — in terms of tools, they are all there. A willingness to learn, coupled with a world class talent like Robbie Keane taking him under his wing — the ingredients are all there.

But in our haste to try and crown the next great American striker, it’s important to realize just how quickly we are getting ahead of ourselves. It’s time we pumped the brakes on the Gyasi Zardes hype train. Not because he doesn’t have it in him to become a truly great player – he does – but because the numbers suggest a statistical inflation that simply cannot be ignored.

Has Gyasi improved from last year? Yes. But not as much as people think. Is he as good as the strikers around him in the Golden Boot race? Almost certainly not. Not yet anyway. Not until he improves those underlying expected goals numbers.

Luckily, Gyasi seems to keep himself above the hype and focused on improvement — a focus that shines through in Gyasi’s everyday interactions with the media. Like this, after the New England game:

Scott French: You’re getting a reputation around the league.

Gyasi Zardes: Am I?

Scott French: Yeah.

Gyasi Zardes: I wouldn’t know.

Adam Serrano: A positive one.

Scott French: You put away this many goals, and people tend to sit up and take notice.

Gyasi Zardes: Yeah, I don’t pay attention to that. You know me. Just trying to stay humble, and stay in my own lane.