Welcome back, readers. Last time, we set the parameters for identifying the best four-seam fastball hitter among the 2021 Boston Red Sox. We established CSW% and smashes per swing as the two metrics we used to help us along on this journey. In terms of the lowest CSW% on four-seamers. The youngster Jarren Duran had the lowest mark at 7.6%. As for smashes per swing newcomer, Kyle Schwarber has accumulated a 10.5% rate, which leads the way so far for this year’s Red Sox (remember these stats were collected as of August 29th).
Our next step is to turn these two metrics into z-scores and eventually combine them. When we come to that average, we can then determine if this truly tells us who is best or if we will have to do even more digging. For even more context, we are going to be calculating the z-scores from just Red Sox players. Resources are a little limited, so league averages won’t be able to be used. We will use the team average. Either way, this should be fun, let’s get it.
CSW & Smash Z (Method 1)
| Player | CSW Z | Smash Z | Total |
| Kyle Schwarber | 1.04 | 1.70 | 2.74 |
| Hunter Renfroe | 0.37 | 1.51 | 1.88 |
| Kevin Plawecki | 0.29 | 1.12 | 1.41 |
| Marwin Gonzalez | 0.54 | 0.70 | 1.24 |
| J.D. Martinez | 0.95 | 0.07 | 1.02 |
| Enrique Hernandez | 0.75 | 0.11 | 0.86 |
| Xander Bogaerts | 0.70 | 0.15 | 0.85 |
| Rafael Devers | -0.95 | 0.93 | -0.02 |
| Jarren Duran | 1.20 | -1.25 | -0.05 |
| Alex Verdugo | 0.16 | -0.65 | -0.49 |
Schwarber leads the team by a pretty good margin. The newest Red Sox slugger has missed a few games during the season because of a hamstring injury, but he’s had enough of a sample size to prove himself pretty potent against four-seamers.
The rest of the leaderboard does consist of some surprises. If you’re familiar with the Red Sox, you’d expect to see the likes of Devers or Bogaerts in the top three, but instead you see Plawecki and Renfroe. Renfroe is having a career year, so this shouldn’t be much of a surprise that he is smashing the ball.
So, we have this method, but let’s switch things up a little. We’re going to change the definitions. Instead of called strikes being a factor, we are going to replace that with whiffs per swing. This method won’t penalize hitters for taking fastballs. On top of that, we will replace the “smash” rate with barrels per swing.
Whiffs and Barrels Per Swing (Method 2)
| Player | Whiff/Swing Z | Barrel/Swing Z | Total |
| Kyle Schwarber | -0.28 | 2.62 | 2.34 |
| Hunter Renfroe | 0.31 | 1.81 | 2.12 |
| Kevin Plawecki | 0.94 | 0.31 | 1.25 |
| Enrique Hernandez | 0.48 | 0.31 | 0.79 |
| Xander Bogaerts | 0.82 | -0.18 | 0.64 |
| J.D. Martinez | -0.08 | 0.37 | 0.29 |
| Marwin Gonzalez | 0.60 | -0.31 | 0.29 |
| Alex Verdugo | 0.72 | -0.62 | 0.10 |
| Rafael Devers | -1.33 | 1.18 | -0.15 |
| Christian Vazquez | 0.73 | -1.56 | -0.83 |
The duo of Schwarber and Renfroe remain at the top. Again, backup catcher Kevin Plawecki has made his way into the top five of the team. In his limited time, he has shown that he makes good contact. Having him at the top of this list and Devers at the bottom proves that baseball can be a strange game.
To see if this Plawecki Cinderella story is real, we will combine all four numbers together. With these powers combined, we can now present the 2021 Red Sox’ best four-seam fastball hitters. By fusing CSW%, whiffs per swing, barrels per swing, and “smash” rate we have reached our conclusion.
Combined Totals (Method 3)
| Player | CSW Z | Smash Z | Whiff Z | Barrel Z | Total |
| Kyle Schwarber | 1.04 | 1.70 | -0.28 | 2.62 | 5.08 |
| Hunter Renfroe | 0.37 | 1.51 | 0.31 | 1.81 | 4.00 |
| Kevin Plawecki | 0.29 | 1.12 | 0.94 | 0.31 | 2.66 |
| Enrique Hernandez | 0.75 | 0.11 | 0.48 | 0.31 | 1.65 |
| Marwin Gonzalez | 0.54 | 0.70 | 0.60 | -0.31 | 1.53 |
| Xander Bogaerts | 0.70 | 0.15 | 0.82 | -0.18 | 1.49 |
| J.D. Martinez | 0.95 | 0.07 | -0.08 | 0.37 | 1.31 |
| Alex Verdugo | 0.16 | -0.65 | 0.72 | -0.62 | -0.39 |
| Rafael Devers | -0.95 | 0.93 | -1.33 | 0.93 | -0.42 |
| Jarren Duran | 1.20 | -1.25 | -0.81 | -0.62 | -1.48 |
Are these really the best four-seam hitters the Red Sox have to offer? Going off this, there is no reason to believe that they aren’t. Kyle Schwarber and Hunter Renfroe are putting up some of the best numbers of their respective careers. In Schwarber’s case, he’s shown that he doesn’t take too many strikes and when he makes contact he does plenty of damage. So congratulations to Mr. Schwarber. He is the Red Sox’ king of four-seamers (at least through August 29th).
Main Photo:
Players Mentioned:
Jarren Duran, Kyle Schwarber, Hunter Renfroe, Kevin Plawecki, Marwin Gonzalez, J.D. Martinez, Enrique Hernandez, Xander Bogaerts, Rafael Devers, Alex Verdugo, Christian Vazquez
