Jason Heyward and Anthony Rizzo are two of the best players in Major League Baseball, and absent arguments from their teams' third basemen, they might be the best position players on the St. Louis Cardinals and the Chicago Cubs, respectively. Both players play in the field, they are both recently-turned 26 years old, and they both hit at an above-average clip, but their production is greatly varied. Rizzo has 30 home runs and 145 wRC+ to Heyward's 12 homers and 117 wRC+ yet Heyward has the edge in fWAR 5.2 to 4.9 and in bWAR at 6.1 to 5.8 making both players roughly equivalent. Attempting to account for a player's total value can be difficult, but Heyward's baserunning, position on the field, and defense make up the difference in value.
Many who read this piece are familiar with the various versions of WAR, how they work, and generally what they mean and how to use them. Most of the time, WAR is the endpoint, the number we use to compare players that some take as gospel, many deride as worthless, while many others attempt to understand the nuances to a statistic with great broad-ranging use. For the purpose of this piece, I am going to forget about WAR for the bulk of what is written below. Let us forget about WAR for a bit, and just try to start over when comparing two very different players in Jason Heyward and Anthony Rizzo. I cannot promise there will be no math, but I will do my very best not to beat anybody over the head with numbers and formulas.
Generally, when we watch non-pitchers play baseball, we see them doing them doing three things: hitting a baseball, running the bases, and fielding their position. Hitting a baseball draws the most focus because it occurs regularly and every time somebody comes up to the plate, the focus is on a singular match-up involving principally the hitter and pitcher. When comparing two players, let's start with hitting. Below are the most relevant statistics for hitting, in my opinion, along with the lines for Rizzo and Heyward as well as the difference between the two (through Sunday).
Along with plate appearances, the above chart contains all of the positive outcomes for a hitter. Based on the above, Rizzo looks like a much better player: more home runs and more times getting on base. The problem comes when we attempt to figure just how much better Rizzo is on offense. As the goal of any offense is to ultimately score as many runs as possible, turning the events above into runs is probably ideal. I am going to weight each event as I see fit. Slugging percentage makes a home run worth four times a single, twice that of a double, and gives no credit for walks. A home run is a great outcome, but I don't think it is worth four times a single. Here are approximations for my weights:
A walk is worth something, but not as much as a hit, and a home run is worth close to two-and-a-half times as much as a single. These might look arbitrary, but they are based on a lot of math that I do not care to get in to. I will say that the math is done by looking at every possible situation in terms of outs and runners and looking at how many runs score in those situations. You could make up your own numbers and get different results, but these numbers look like an approximate weighting of the different events even if we did not have the math behind it.
Taking the difference in the values from above, we create the following chart:
Adding up that bottom column get us to a total difference of about 25 runs on the hitting side.
Next, let's take into account baserunning. Without going over everything above, let's say a stolen base is worth .2 runs and a caught stealing is worth about negative .4 runs. Heyward has 23 steals and has been caught just three times, adding about 3 runs while Rizzo has stolen 17 bases and been caught six times, adding one run. Both players have done a good job running the ball out on potential double plays. When going first to third and second to home, Heyward is one of the very best in the game, adding another three runs, while Rizzo is not as adept. Add all those totals up and Heyward is roughly 6 runs above average while Rizzo is one run above average.
A deficit that was once 25 runs is down to 20 between the two.
Now we factor in the defense. The two players play different positions, with Heyward playing the more difficult one in right field (sometimes center field) while Rizzo only plays first base. Trying to quantify how many runs this difference is worth can be difficult. For the purposes of this dicussion, I'm going to look at the number of runs above average first baseman are on offense in 2015 using the same methods from above (452) and compare that to right fielders (294). Generally speaking, teams are going to put players in the most difficult defensive position they can handle, and different levels of offense are acceptable depending on that difficulty. Overall this season, first baseman have hit better than right fielders by 158 runs, around five runs per team. Both RIzzo and Heyward are full-time players, so let's call it five runs.
Shrinking the gap by another five runs cuts the difference down to 15.
That is not the only factor to consider when we look at defense as we can examine the quality of play of each player compared to average at the position. There are two main defensive metrics we can use: UZR and DRS. Both metrics attempt to quantify how many runs are saved by a player at his position compared to average. They account for how many potential hits are taken away, using similar values to the values in the chart above, and how many bases are saved with the player's arm.
Rizzo's numbers are not great this season, but over the past few seasons he has been above average at first base. Averaging the last three years to get a sufficient sample size, by DRS, he has been about ten runs above average and by UZR, he has been closer to five--splitting the difference between the two puts us at, let's say 8.
Heyward has been superlative on right field by both metrics. Weighting his 2013 year slightly given that he played just two-thirds of the season, Heyward has been 25 runs above average by DRS and 20 runs above average by UZR--splitting the difference puts us at 23.
A few paragraphs up we were at 15 runs difference. With another 15 runs difference in fielding, we have roughly equivalent players. A run saved is just as valuable as a run scored and while Rizzo combines great offense with decent defense at a position that is fairly easy to play, Heyward combines above average offense with great defense at a position that is a bit more difficult. It might not always be easy to "trust" defensive metrics because we know less about them, but making some fairly reasonable assumptions closes the gap between Rizzo and Heyward and makes them both two of the very best players in the game.