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What do the metrics say about Vaughn Grissom?

Grissom emerged into the MLB scene on fire. Should we expect that again?

MLB: Atlanta Braves at Philadelphia Phillies
Atlanta Braves’ Vaughn Grissom
Kyle Ross-USA TODAY Sports

The start of the season for the Atlanta Braves is almost here, and all eyes are on young Vaughn Grissom. Fan favorite Dansby Swanson is now on the Cubs, and the hope is that his heir apparent can take over and be a steady force for years to come.

Now, Grissom being the shortstop of the future is not guaranteed. If we look at older scouting reports, we see that he was not viewed as a shortstop long term in the majors. However, Ron Washington has been working with him, and it appears that going into 2023, he has the best chance of being the everyday starter.

With Elvis Andrus being arguably the best available free agent shortstop, and signing elsewhere, it leaves the battle being between Grissom and Orlando Arcia.

Arcia did arguably have his best season last year, but it was at 2B, and his defensive metrics show that he is slowing down in that regard.

All of this seems to point to Grissom, so let’s look at his metrics last year and see what we should expect.

Can Grissom continue his emergence at his current rate?

At least from an offensive standpoint, Grissom came into MLB on fire. In 156 plate appearances through 41 games, Grissom had a slash line of .291/.353/.440 which was good for a 121 wRC+ (21.0 percent better than league average), a wOBA of .345 and an fWAR of 0.7.

If we look at Fangraph’s FGDC projection, Grissom is projected to have a wRC+ of 100 (right at league average), a wOBA of .315, and an fWAR of 1.9 through 469 plate appearances and 109 games. For reference, if Grissom would have played 109 games in 2022 he was on pace for 1.86 fWAR.

But, wait, a 21.0 percent drop off in wRC+ and a .030 drop off in wOBA are substantial, so what gives?

Well, if we look at his first 103 plate appearances through 26 games, the surface numbers are fantastic. .347/.398/.558 is the type of slash line any manager would drool over.

However, his final 53 plate appearances through 15 games were not so promising with a slash line of .174/.264/.196.

Was Grissom lucky in his first 26 games and unfortunate in his last 15? BABIP points to yes. He had a well above league average BABIP of .389 (league average was .298 in 2022) in his first 26 games, and a below average .258 in his last 15.

BABIP is a great tool, but is always best practice to dig even deeper. If we look at his wOBA by month, we can see what the slash lines tell us. In August he had a fantastic 0.360 wOBA (league average was .338 in 2022), but in September it was down to .329.

Rolling wOBA

If we look at his XSTATS we can see that did arguably get lucky, which is common place in small sample sizes. In the month of August we see that his expected wOBA (xwOBA) had him at .337 which was just below league average during his hot stretch. Then, during his cold stretch in September, he was still over performing in terms of his wOBA, because his xwOBA was 0.316.

Rolling xwOBA

Based on his differences in his wOBA and xwOBA over an extended period of time, Grissom would have a lower slash line over a full season than what he did in limited action in 2022.

We can look at more traditional stats to see the big differences in XSTATS and true output. In August, Grissom had a batting average of .311, but his xBA was .285. In September he had a batting average of .269, his xBA was .230. It is the same story with slugging. In August he had a slugging percentage of .473, but a xSLG of .441. In September he had slugging percentage of .403, but an xSLG of .380.

Besides the XSTATS differences, are there any other areas to keep an eye on?

For some strange reason, it appears that Grissom just forgot how to hit a breaking pitch. He saw 98 breaking pitches in August and 97 in September, so that sample sizes are as about as even as you can get, yet the rate stats are drastically different.

In August, against breaking pitches Grissom had a wOBA of .365 (league average in 2022 was .272), and an xwOBA of .390. It was looking like Grissom had the potential to be an elite hitter against breaking pitches.

However, in September his performance against them took a nose dive. His wOBA against breaking pitches was .171, and his xwOBA was .273. The bright spot is that September was a small sample size, and his xwOBA is showing he was slightly above league average (.268).

Rolling wOBA by pitch type

Ultimately, his downfall against the pitch was due to a few reasons. First, that he was swinging and missing more. His whiff rate sky rocketed from 32.3 percent in August to 44.4 percent in September. His quality of contact dropped as well. In August his average exit velocity (EV) against breaking pitches was 84.2 MPH with a launch angle of 8 degrees. In September his EV dropped to 73.9 and his launch angle was -3 degrees.

What about defense?

There is not much data on Grissom in such a small sample size when it comes to defense, but Fangraphs’ defensive runs saved and ultimate zone rating did not favor his work at 2B. In 347.0 innings, Grissom had -3 DRS and -1.8 UZR. He also had -5.0 Outs Above Average.

Baseball Reference also rated Grissom poorly with a -0.3 dWAR.

Based on Fangraphs’ predictions of 1.9 fWAR in 109 games, yet a large drop off in offense, it appears that it is predicted that his defensive value will improve. Of course, WAR factors in defensive positon value as well, so that is playing a factor.


Based on Grissom’s advanced metrics, it does makes sense that he is projected to have a drop off in offense. However, Grissom is most likely going to be the number 8 or number 9 hitter in most cases. A team that has a league average hitter in terms of wRC+ at the back end of the order is in a really good spot. Grissom may not have a 2022 Dansby Swanson type year, but he does not need to.

If Grissom can gain back his elite ability to hit breaking pitches that he displayed in August, and truly does get better at defense, watch out.

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