2023 Mariners Defense Against the Astros: Their Batters, Our Pitchers

Division Series - Seattle Mariners v Houston Astros - Game Two
Division Series - Seattle Mariners v Houston Astros - Game Two / Bob Levey/GettyImages

There is some debate in the scientific community as to why some people tend to use one hand or the other when they are young and then as adults. In a Scientific American article, the theory is that as people evolved to use speech and language, they increasingly used the left hemisphere of the brain. Since the left hemisphere also controls the right side of the human body, most humans became right-handed, almost 85 percent. This same article also explains an interesting genetic theory.

In baseball, left-handedness or right-handedness is important for batting, throwing, and pitching. Because about 25 percent of the pitchers are left-handed, this imbalance can affect the meeting of two teams. We have two left-handed starting pitchers: Robbie Ray and Marco Gonzales. George Kirby, Logan Gilbert, and Luis Castillo pitch with their right hands.

For today's article (The first in a limited series), let's take a look at how the Mariners pitching matches up against the Astros hitting from an RHP/LHP vs RHB/LHB standpoint, dependent on the particular type of matchup.

The Batters: the Astros on Offense

Some of the Astros players bat equally well against left-handed and right-handed pitchers according to split statistics from ESPN. These batters are Yordan Alvarez and newly acquired José Abreu. The rest of the players who may make up the starting lineup have a real preference according to their 2022 stats.

Players who bat better against left-handed pitchers: Jose Altuve, although his OPS (On Base Percentage plus Slugging percentage) is .860, so it may not matter; Jeremy Peña, Chas McCormick, and Martin Maldonado

Players who bat better against right-handed pitchers: Alex Bregman, Kyle Tucker, and Michael Brantley.

The Pitchers: Mariners on Defense

Looking at our starting pitchers, we have a mixed results in terms of who has more success with right and left-handed batters. These 2022 individual stats are for all innings pitched in the regular season, not only against the Astros.

  • Luis Castillo (RHP) has an OPS of .635 for lefties and .589 for righties (slightly stronger with righties)
  • Robbie Ray (LHP) has an OPS of .647 for lefties and.740 for righties (stronger with lefties)
  • Logan Gilbert (RHP) has an OPS of .579 for lefties and .773 for righties (stronger with lefties)
  • Marco Gonzales (LHP) has an OPS of .811 for lefties and .770 for righties (slightly stronger with righties)
  • George Kirby (RHP) has an OPS of .533 for lefties and .846 for righties (much stronger with lefties)

Last season, the Mariners’ starting pitchers were more successful against left-handed batters than right-handed batters overall. Gilbert and Kirby have more typical right-handed success with lefties. Luis Castillo shows about the same percentage for righties and lefties as does Gonzales, and Ray has had better success with lefties over righties.

Unfortunately, a greater percentage of players bat with their right hands. On the Astros, as of now, only three significant batters are left-handed: Yordan Alvarez, Michael Brantley, and Kyle Tucker.


Pitching to the Astros means putting Mariners starting pitchers who are more successful with lefties, statistically, against a primarily right-handed lineup. Statistics are not the whole story, however, as we saw in the postseason against the Astros. Our right-handed pitchers did extremely well. (It is still fun to say postseason.)

  • Pitching coaches, please work with our pitchers to throw more effectively to righties.
  • With the departure of Erik Swanson, we have no left-handed pitchers in the bullpen. Gabe Speier and/or Brennan Bernadino would be helpful additions.

It will be interesting to see how numbers match up when the Mariners are on offense against the Astros.