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Sean Burroughs is not content with being one of the best hitting
prospects in all of baseball. He also wants to make his mark in the field of
sabermetrics.

In an interview with David Schoenfield, ESPN.com editor and one of the most
underrated members of the sabermetric revolution, Burroughs gave a novel
answer as to why his long-awaited power had still not arrived (he’s hitting
.352 in Triple-A, but with only five home runs in 236 at-bats.) Referring to
the fact that he bats left-handed but throws right-handed, Burroughs said:


I think it takes a little more time for our power to develop. Our dominant
hand is our right hand, but you need power from both hands when you hit.
Guys like [Ken] Griffey and [Barry] Bonds, they're
lefty-lefty.

Burroughs also pointed out fellow Futures Game teammate Adam Dunn,
also a left-handed hitter but a right-handed thrower, who after hitting
"just" 27 home runs over the past two years, already has hit 30
this season.

Is Burroughs on to something? It’s true that Ken Griffey Jr., a lefty all
the way around, was dropping bombs in the right-field bleachers from the
time he was a teenager. And as Schoenfield writes, "it’s an interesting
concept, especially since Burroughs is often compared to George
Brett
, a lefty-swinging, righty-throwing third baseman who hit only 20
home runs his first three years in the majors."

The anecdotes piqued our interest, but to test Burroughs’s hypothesis,
anecdotes won’t suffice: we need hard data. Fortunately, we have it.

>From 1920–when home-run power became relevant–through 1993, a total of 318
players have batted 250 or more times in a major-league season at age 21 or
younger. (The same player can be counted more than once; Griffey, for
example, qualifies three times.) Of those 318, only 118 batted exclusively
left-handed. Of those 118, 43 throw left-handed (we’ll call them
L-L), and 75 throw right-handed (L-R).

Using Isolated Power (slugging average minus batting average) as a measure
of power, we can divide players into five different cells: less than .080,
.080-.120, .120-.160, .160-.200, and greater than .200. So we can break
these 118 players down this way:


Power      Throws L     Throws R     Total

>.200 2 12 14 .160-.200 10 5 15 .120-.160 13 14 27 .080-.120 14 30 44 <.080 4 14 18

This breakdown defies any obvious trend. On one hand, L-R hitters were
responsible for 12 of the 14 seasons with the most left-handed power before
age 22. The only two L-L hitters with an isolated power above .200 were
Griffey (1991) and Darryl Strawberry (1983). Among the L-R hitters,
Mel Ott did it three times by himself, Ted Williams and
Eddie Mathews twice each.

But the rest of the chart indicates that, on average, L-L hitters show more
power than L-R hitters. Twenty-five of the 43 L-L hitters (58%) had an ISP
of .120 or higher. Just 31 of 75 L-R hitters (41%) did the same. Overall,
the 43 L-L hitters under age 22 had an ISP of .136. The 75 L-R hitters had
an ISP of .131, a five-point difference.

Is that significant? Maybe not. Left-handed-throwing infielders (except for
first basemen) are as rare as a funny skit involving Tim Meadows, owing to
the fact that a left-hander would have to pivot awkwardly when throws to
first base. Left-handed-throwing catchers are also essentially non-existent,
although I have yet to hear a good reason why.

So it would stand to reason that L-L hitters would have more power than L-R
hitters anyway, because L-L position players can only play first base or the
outfield. If we look at a control group by comparing L-L hitters vs. L-R
hitters at, say, age 30, we find that L-L hitters have a combined ISP seven
points higher (.145) than L-R hitters (.138). That disparity is two points
higher than the difference between young L-L and L-R hitters, although the
difference between the two numbers is probably not statistically
significant.

To put it in simple terms--in case Allard Baird is reading this Web site for
the first time--among left-handed hitters who make it to the major leagues
at an early age, those who throw left-handed appear no more likely to
exhibit precocious power than those who throw right-handed.

But that isn't exactly the point Burroughs was trying to make. His claim is,
in essence, if two young left-handed hitters both show only modest power,
the one who throws right-handed is more likely to develop power in the
future than the one that throws left-handed.

Let's get back to the chart above. In particular, let's focus just on the
bottom row, which contain the players with the least power:


Power      Throws L     Throws R     Total

<.080 4 14 18

A total of 18 players under the age of 22 have had an isolated power of
under .080. At this point in time, the two groups of hitters, L-L and L-R,
have virtually identical power totals; the L-L hitters have an ISP of .059,
the L-R hitters .061. If we fast-forward and look at how the players perform
five years later, do the L-R hitters hit for more power than the L-L hitters
do?

Only two of the four L-L hitters were still playing regularly five years
later, and they combined for an ISP of .119. Nine of the 14 L-R hitters got
250 PA's, and their combined ISP was .095.

Summarizing these findings in yet another chart:


             Bats L, Throws L             Bats L, Throws R
Power   Year 0  ISP   Year 5  ISP     Year 0  ISP   Year 5  ISP   Diff

<.080 4 .059 2 .119 14 .061 9 .095 -26

"Difference" refers to how much L-R hitters improved relative to
L-L hitters. In this case, L-R hitters saw their ISP increase by 34 points
five years later, compared to the 60-point increase enjoyed by L-L hitters.
Since the L-R hitters improved by 26 points less than the L-L hitters, they
earn a "Difference" of -26.

That's a very small sample, so let's do the same with each of the rows in
the original chart:


             Bats L, Throws L             Bats L, Throws R
Power   Year 0  ISP   Year 5  ISP     Year 0  ISP   Year 5  ISP   Diff

>.200 2 .224 2 .301 12 .246 10 .198 -125 .160-.200 10 .185 8 .170 5 .168 5 .160 +7 .120-.160 13 .140 11 .175 14 .136 10 .170 -1 .080-.120 14 .099 10 .111 30 .098 24 .139 +29 <.080 .059 2 .119 14 .061 9 .095 -26

The top row is skewed by the incredibly small sample size of the L-L
hitters, as Griffey is a future Hall of Famer and Strawberry looked like one
for the first seven years of his career. Overall, there does not appear to
be an obvious advantage for either the L-L or the L-R hitters. However, that
29-point advantage enjoyed by the L-R hitters in the next-to-bottom row
looks intriguing, especially since the sample size is the largest of all the
rows.

Now we'll look at the same chart, but change the criteria to look at
slightly older hitters, guys who were 22 or 23 years old in their original
season. Those players are still young enough to develop power as they age,
and looking at older players provides us a much larger sample size to
examine the issue. In addition, we'll eliminate the top two rows entirely,
because those players have already shown they can hit for power, so they
really aren't germane to the question at hand.


             Bats L, Throws L             Bats L, Throws R
Power   Year 0  ISP   Year 5  ISP     Year 0  ISP   Year 5  ISP   Diff

.120-.160 45 .141 37 .154 6 .137 45 .155 +5 .080-.120 39 .098 22 .113 60 .103 38 .120 +2 <.080 16 .060 10 .108 39 .062 22 .107 -3

The increased sample sizes have helped to smooth out the data, and what the
data shows is that there's no real difference between the two groups.

We could tweak the study in many other ways, lowering the PA requirement,
looking three years ahead instead of five years, whatever. I'll agree to
spare you the tedium of looking at more lists if you'll agree to trust me
when I tell you that none of them show any significant difference between
the two groups.

There's one other factor we should consider, though. We've already
established that the lack of L-L middle infielders and catchers means that,
overall, L-L hitters have more power than L-R hitters. It has also been
shown (by Bill James, in the 1987 Baseball Abstract) that, presumably
owing to the physical demands of their positions, second basemen and
catchers tend to develop less than players at other positions. Since there
are no L-L hitters at either position, is it possible that if we match
players from each group with players at the same position, that a difference
between the two groups will finally emerge?

Only one way to find out. The following chart consists only of players who
were 22 and younger, and who were primarily outfielders during their
original season (defined as 50 or more games played in the outfield):


             Bats L, Throws L             Bats L, Throws R
Power   Year 0  ISP   Year 5  ISP     Year 0  ISP   Year 5  ISP   Diff

.120-.160 18 .144 15 .162 23 .139 15 .167 +10 .080-.120 21 .100 19 .121 23 .104 19 .145 +20 <.080 7 .068 4 .115 12 .066 9 .107 -6

There might--stress might--some evidence here to back up Burroughs' claim.
The L-R hitters do not fare well in the bottom row, but the sample size is
by far the smallest of the three groups, and the advantages shown by the L-R
hitters in the other two groups are fairly sizable. If we combine all three
rows together, giving us a total sample size of 38 L-L and 43 L-R seasons in
the follow-up group, L-R hitters have an overall advantage of 11 points of
isolated power.

I imagine there's a way to determine whether a difference this large, in a
sample this large, is statistically significant or not. Unfortunately, I
neglected to take that particular class in college, so I'm forced to use
inference to determine whether the difference is real or not. And there is
at least one additional reason to believe that the advantage enjoyed by
young L-R hitters is real: the advantage appears to fade as the players age.
The 11-point edge for L-R hitters includes all outfielders 22 and under. If
we look solely at outfielders 21 and under, the advantage is actually 13
points; for 22-year-olds, it slips to seven points. Among 23-year-old
outfielders, there doesn't appear to be any advantage at all; in fact, L-L
hitters actually fare two points better than L-R hitters.

Nevertheless, I'm not willing to hang my hat on Burroughs's statement just
yet. To reach a firm conclusion would require a study of hundreds of
hitters, and there simply isn't enough data available, at least not in the
major leagues. A study including minor-league players would feature enough
young players, but trying to compare hitters at various minor-league levels
might only muddy an issue that is murky enough as it is.

And even if the L-R advantage is real in statistical terms, is it
significant in baseball terms? Suppose we use the most generous evidence in
the study and project a young L-R player like Burroughs (who is still just
20 years old) to pick up an extra 13 points of slugging average relative to
his L-L counterpart, say someone like Josh Hamilton, over the course
of the next five years. Thirteen points of slugging average comes out to
about seven total bases over the course of a season, the equivalent of
converting three singles into a double and a pair of home runs. That's not
trivial, but neither is it large enough to change the outlook of a young
player one way or the other.

Or to put it another way: if Burroughs develops the 25-homer power that
everyone expects from him, there will be no reason to think he wouldn't have
developed his home run swing had he thrown with his left hand.

Rany Jazayerli is an author of Baseball Prospectus. You can contact him by
clicking here.