Is Luis Castillo the Reds’ MVP so far? Or how about Tanner Roark?

Is Luis Castillo the Reds’ MVP to this point in the season?

He is if you believe in the merits of the WAR (Wins Above Replacement) statistic. There are two primary WAR statistical measures that the experts follow: Baseball-Reference.com and Fangraphs.com.

Baseball-Reference.com’s listing of season-to-date WAR statistics (through Monday, June 24) has Castillo at 2.7 WAR, the top number on the Reds roster by far. Fangraphs.com has Castillo at 1.5 Total WAR, fourth on the team. Castillo’s average between the two numbers is 2.1, the highest average WAR number between the two statistical services on the Reds roster.

Fangraphs, the creator of WAR, describes its output this way:

Wins Above Replacement (WAR), FanGraphs’ hallmark statistic, attempts to estimate a player’s total value relative to a free available player, such as a minor league free agent.

We hear a lot about WAR, and I, for one, don’t know the specifics about how it is calculated. Perhaps many of you here at Redleg Nation are in the same boat, and this link to Baseball-Reference’s summary page may help those of you who are advanced mathematicians and statisticians. Here are the basics:

WAR for position players has six components, at least in the Baseball-Reference computation:

Batting Runs
Baserunning Runs
Runs added or lost due to Grounding into Double Plays in DP situations
Fielding Runs
Positional Adjustment Runs
Replacement level Runs (based on playing time)

The first five measurements are all compared against league average, so a value of zero will equate to a league average player. Less than zero means worse than average, and greater than zero means better than average. These five correspond to the first half of our equation above (Player_runs – AvgPlayer_runs). The sixth factor is the second half of the equation (AvgPlayer_runs – ReplPlayer_runs).

Replacement level is something of a touchy subject with non-sabermetricians, and probably the least understood of the ideas here.

Currently, we set replacement level at .294 winning percentage (changed from .320 in March 2013) for the major leagues, which means there are 30*162*(.500-.294) = 1,000 Wins above replacement in the major leagues as a whole.

The wins, and therefore the runs, are further divided between pitchers and position players. We assign 41% to the pitchers and 59% to the position players. This corresponds to the salaries of free agent pitchers vs. hitters over the last four seasons.

On offense, this division and replacement level corresponds to 20.5 runs over the course of 600 plate appearances. So, if a team replaced a league-average starter with a replacement player we’d expect a 20 run difference in their run differential. We call this 20.5 runs the Replacement Level multiplier.

Pitcher WAR is computed differently, and you can understand why.

At its most basic level, our pitching WAR calculation requires only overall Runs Allowed (both earned and unearned) and Innings Pitched. Since we are trying to measure the value of the pitcher’s performance to his team, we start with his runs allowed and then adjust that number to put the runs into a more accurate context.

Fangraphs, on the other hand, computes the number this way for pitchers and this way for position players. Both respected services have the same goal, but different assumptions on how it is best computed and measured.

WAR statistics make it clear that pitchers have been the Reds’ most valuable players to date:

For some frame of reference, here are the Major League leaders in average WAR:

Cody Bellinger, 5.8; Mike Trout, 5.25; Christian Yelich, 4.7; Max Scherzer, 4.05. You can see that the players atop this statistical category are the players considered by many to be the best in the game today.

And, on the other side of the coin are pitcher Dan Straily and shortstop Richie Martin, Jr., both of the Orioles, at -1.2 WAR. (*Fangraphs number only; Baseball-Reference.com number could not be located to create an average.) Straily was recently designated for assignment. The Reds’ low in WAR is Matt Kemp, at -0.8. Like Straily, he was not kept around.

If Bellinger keeps up his current pace, he’s headed for a double-digit WAR season, as is Trout. In that case, the statistic would indicate that Bellinger’s presence in the Dodger lineup meant 11 more wins for the team than if a minor leaguer was playing in his stead. In some ways, its comparable to the way pitchers were measured for most of the first 150 years of professional baseball, by their wins and losses.

The Reds numbers are not surprising, but they do reinforce what we already knew — the pitchers are the key performers on the team, at least to this point, and four of the top six WAR Reds players were acquired by the front office before the season.

And, it looks like the team’s MVP might be a pitcher for the first time since Johnny Cueto in 2014.