Adeiny Hechavarria's defense shined on the field and the stat sheet for the Miami Marlins last season.
We often watched in wonder as he made near impossible plays seem routine. Hechavarria's great defensive season made him a strong golden glove candidate, as he came up just short to San Francisco Giants' star Brandon Crawford. Many people believe he will continue to impressive defensively, but this is a risky assumption. Hechavarria had an elite defensive season last year, but this does not mean he is an elite defensive player.
While defense is notoriously difficult to measure, sabermetric analysts have developed multiple ways to determine a player's fielding prowess. In 2015, Hechavarria had an elite defensive season no matter which metric you look at. However, one of the most common misconceptions regarding single season defensive statistics is that they give a strong indication of a player's defensive ability. All sabermetric analysts will tell you the same thing when looking at a data set: the larger the data set, the better. Therefore, one season of defensive statistics is not enough data to determine Hechavarria's skill.
Data Set Limitations:
Sample size is important with defensive metrics because of the scarcity of plays a fielder is actually involved in during the course of a game. For example, during the May 5 game against the Washington Nationals, Hechavarria only participated in four defensive plays:
1. In the third inning, he was involved in a 4-6-3 double play.
2. In the fourth inning, he fielded a relatively easy short hopper and threw Wilson Ramos out at first base.
3. In the sixth inning, he fielded an easy hopper hit straight at him and threw Ryan Zimmerman out at first base.
4. In the ninth inning, he committed an error dropping an easy force out at second base.
Hechavarria committed an error on 25 percent of the plays in which he was involved. Is it fair to extrapolate his performance vs. the Nationals to predict his performance in future games? Absolutely not. Furthermore, how much do "easy plays" tell us about a player's fielding ability, and how much statistical power do these plays actually have? That is difficult to answer, but typically a season worth of defensive statistics does not carry the same "weight" as a season worth of offensive statistics. Therefore, we need a sample size larger than the 2015 season to determine Hechavarria's defensive ability.
One of the most popular defensive metrics, and my personal favorite, is Michael Lichtman's ultimate zone rating (UZR) measurement. Like all sabermetric stats, it is incredibly dependent on data set size. A larger data set means that the UZR value is more indicative of a player's true defensive skill. You can read a simplified explanation of UZR on the Fangraphs website here or a more detailed in-depth look here. I will offer a quick overview of UZR before we dive into Hechavarria's stats.
UZR, like many sabermetric stats, attempts to quantify the number of runs saved or allowed by a player to determine his positional defensive value. Essentially, the field is split into 78 zones of which 64 are used to calculate UZR. Each position has a number of zones for which it is responsible.
First, it is determined how likely an "average player" will successfully complete a play when a ball is hit into one of his position's designated zones. Next, the likelihood an individual player completes a play in that zone is determined: if he completes more plays than the "average player" he receives a positive UZR rating, if he completes less plays than average he receives a negative rating.
How much a particular play contributes to a player's overall UZR score is dependent upon its difficulty. For example, a difficult ball that is successfully fielded for an out will count more towards a positive UZR than a ball that is easier to field. In contrast, an easier ball that a player fails to field counts more towards a negative UZR than a ball that is difficult to field. Next, additional adjustments are made to the final UZR grade to account for park factor, the handedness of the pitcher, how hard a ball is hit, etc. As you can see, it is an extremely complicated stat, but essentially UZR is split into three categories:
1. Double-Play Runs - the amount of runs saved or allowed by a player due to their ability to turn double plays compared to league average.
2. Range Runs - the amount of runs saved or allowed by a player due to their fielding range compared to league average.
3. Error Runs - the amount of runs saved or allowed by a player due to their susceptibility to commit errors compared to league average.
The sum of these categories equals a player's UZR, with league average being a value of zero. Once again, a positive UZR means a player is above average defensively relative to other players at his position, while a negative UZR means he is below average. Now, let's take a closer look at Hechavarria.
Hechavarria's UZR Rating:
In 2015, Hechavarria finished second in UZR among qualified shortstops behind Andrelton Simmons of the Atlanta Braves. That is excellent, but typically it is assumed that one full season of batting statistics is equivalent to around two seasons of UZR. Therefore, just looking at Hechavarria's 2015 season is an inaccurate depiction of his true fielding ability. We must look at his UZR across as many seasons as possible to get a better sense of his skill. Below, I made a table of Hechavarria's UZR ratings from his 2013-2015 seasons with the Marlins:
Table 1. Hechavarria's UZR across multiple seasons:
From this table, we can see Hechavarria was a poor fielder in 2013 and 2014. In fact, he finished with the 20th ranked UZR out of 22 qualified shortstops (at least 900 innings played) in 2013, and with the 20th ranked UZR out of 21 qualified shortstops in 2014. So not only was he a poor fielder, but he also ranked among the worst starters at his position. His poor "Range Runs" grades are particularly startling because he is generally considered a "big play" shortstop. We are used to seeing him make diving stops like this:
Hechavarria's poor "Range Runs" grade in 2013 and 2014 indicates he actually struggles to complete plays in a shortstop's fielding zones. Have we overrated Hechavarria because we are used to seeing him complete highlight-reel plays? Let's take a closer look at his UZR grade to find out. UZR is a counting stat, so to determine Hechavarria's true defensive value, we can sum his UZR across 2013-2015:
A -2.0 UZR indicates that Hechavarria is a slightly below average defender. However, I would argue this is not a fair assessment of his ability because simply summing UZR values across multiple seasons does not account for player improvement. Instead, we can sum weighted UZR values. Essentially, we add multipliers to more recent seasons to give them more statistical power because we assume Hechavarria has improved from year to year. Below is a weighted UZR formula:
A total UZR of 3.7 seems like a more accurate estimation of Hechavarria's defensive value. He is above average, but not elite.
It is hard to be fully confident in Hechavarria's defensive ability because of his poor play in 2013 and 2014. 2015 seems like a statistical anomaly, because it is extremely unlikely for a player to go from being one of the worst defensive players at his position to one of the best in the matter of a single season. Hechavarria has definitely improved, but he can not yet be considered elite (or even "good") until he can show consistency from season to season.
However, perhaps you wish to rely on the "eye test" and don't agree with the UZR results. I would point out that other highly respected sabermetric statistics, such as Defensive Runs Saved (DRS), also show that Hechavarria was a poor fielder until last season. I would also point out that your eyes do not deceive you. Hechavarria does make a lot of "highlight-reel" plays and statistics even back up this observation. Let's take a quick look at another statistic, Inside Edge Fielding.
Inside Edge Fielding seeks to determines how often a player successfully completes a defensive play of a particular difficulty. Scouts judge every play and group it into one of six difficulty categories:
1. Impossible - Players at a particular position complete this play 0 percent of the time
2. Remote - Players at a particular position complete this play 1-10 percent of the time
3. Unlikely - Players at a particular position complete this play 10-40 percent of the time
4. About Even - Players at a particular position complete this play 40-60 percent of the time
5. Likely - Players at a particular position complete this play 60-90 percent of the time
6. Almost Certain - Players at a particular position complete this play 90-100 percent of the time
From 2013-2015 Hechavarria actually had the highest success rate of any shortstop completing plays of Remote and Unlikely difficulty. He completed 11.8 percent of Remote plays and 50 percent of Unlikely plays. What is startling about these numbers is that he completed above the expected percentage at his position. For context, no other shortstop completed above 10 percent of Remote plays and only three other players (Andrelton Simmons, Brandon Crawford, and Alcides Escobar) completed above 40 percent of Unlikely plays. Our eyes do not lie, Hechavarria contributes to the defensive highlight-reel more than any other shortstop. So, how do we explain his poor UZR ratings?
Ultimately, Hechavarria is less successful at completing easier plays. Compared with other players, he is only slightly above average in his success rate fielding About Even, Likely, and Almost Certain plays. Remember, UZR penalizes players heavily for failing to complete easy plays - this could explain his negative rating in 2013 and 2014.
The combination of UZR and Inside Edge Fielding actually tells us a fair amount about Hechavarria's true ability. Because Hechavarria completes difficult plays at such a high rate, it is safe to assume he has a lot of raw ability. However, his penchant for making mistakes on easier plays indicates he still hasn't put it all together. 2015 was the first season where he truly harnessed his talent to produce excellent results. The question now becomes: can he can show some consistency?
UZR and Inside Edge Fielding statistics were taken from Fangraphs.