Defensive Shifts

In baseball, fans see many kinds of defensive shifts. Let’s focus on the standard infield shift. Major League Baseball defines an official shift as having at least three of the four infielders positioned on one side of second base at the time of the shift.

Why shift? The answer is simple.

“The rationale for the shift is pretty intuitive: Both left-handed and right-handed hitters tend to pull about three-quarters of their ground balls, so it seems smart to position more fielders where the ball is likely to go. Shifts against lefties have been proved to prevent hits on the whole…” — Ben Lindbergh

Let’s look at mindset impacts of shifting on the field of play.

Batter mindset. The shift causes mental stress.

Is the batter flexible enough to successfully switch between approaches at the plate, or maybe switch during an at-bat when shifting is ‘on’ or ‘off’ depending on the pitch count? Possible approaches include:

• Ignore the shift because his approach of swinging with power (and often pulling the ball) is successful. It will continue to be successful with an infield shift.
• Hit more fly balls to avoid grounding into the shift. Hit over the shift. But what if the shifted infield plays back on the grass to reduce the effectiveness of fly balls?
• Make contact and ‘slap’ the ball into the gap. The hitter may be giving up doubles and triples for singles.

A choice is added to a batters complex mental task. As Yogi Berra said, “How can a guy hit and think at the same time?”

Pitcher mindset. Statistics at Baseball Savant (we will look at some shortly) seem to show pitchers walk batters more frequently when the shift is on. The reason is unclear. Are they worried about gaps in the field? Are they pitching to certain parts of the strike zone to take advantage of the shift?

Perhaps the pitchers face the same mental stress as batters: can they adjust their approach when the shift is on?

Fielder mindset. When a fielder stands in a different place, his perspective is changed. His role is changed, how far he throws is different, and what direction he throws is different. For example, a second baseman playing on the third-base side of second base has a farther throw to first, and in the case of double plays he could be throwing to second base instead of catching at second base. And what about the ‘lonely’ fielder who covers about half the infield – does he feel extra pressure?

And what about Gold Glove fielders? They honed their skill at one position to the Gold Glove level, and when they shift their skill-set is either irrelevant or not needed. In 2015, Billy Eppler gave his Gold Glove shortstop Andrelton Simmons a special task: “You’re essentially our quarterback, and you can audible at the line of scrimmage, because you’re going to have more real-time information.”

There is an alternative to shifting or not-shifting.

Matt Trueblood wrote, “However, Maddon’s Chicago Cubs shifted less often in 2019 than any other team in the majors, and they only narrowly avoided the same distinction in each of the three previous seasons. Maddon elected to do other things to maximize his team’s chances of converting batted balls into outs — things like moving defensive whiz Javier Baez around the infield, swapping first baseman Anthony Rizzo to second base when the opponent was likely to lay down a would-be sacrifice bunt and asking superstar slugger Kris Bryant to split time between third base and right field.”

Maddonism: Put the best defenders where the ball is most likely to go.

Other Maddonism can be found at the bottom of this AZ Snake Pit series preview.

Does shifting improve defense?

To address that question, much has been written. In 2020, left-handed batters faced the shift more often than right-handed batters (50.1% vs 22.9% of pitches). It is generally agreed that infield shifting works against left-handed batters. There is disagreement on whether it works against right-handed batters. Let’s leave that complex and lengthy discussion for another time and place.

Let’s look at defensive shifting by the Diamondbacks in 2020.

The Diamondbacks’ Defensive Runs Saved (DRS) from infield shifting (data from The Fielding Bible) fell from 33 in 2019 to 2 in 2020. Adjusting for the shortened season, 2 DRS is equivalent to 5.4 DRS, which is much lower than 2019.

How did infield shifts impact wOBA? Let’s compare wOBA with and without shifting for each pitching count and for each team the Diamondbacks played. Instead of overwhelming you with numbers, the following chart will use H to mean higher wOBA when shifted and L to mean lower wOBA when shifted. NS will mean not significant either because 3-or-less shifted PAs or because the difference was very small (.01).

Data from Baseball Savant.

Four observations follow:

Shifting lowered strikeouts-per-plate-appearance for all 2-strike counts. Fewer strikeouts lowered the defensive value of shifting. Data from Baseball Savant.

• 0-2 Lowered strikeouts-per-plate-appearance from .532 to .500.
• 1-2 Lowered strikeouts-per-plate-appearance from .485 to .445.
• 2-2 Lowered strikeouts-per-plate-appearance from .451 to .445.
• 3-2 Lowered strikeouts-per-plate-appearance from .274 to .252.

Shifting raised walks-per-plate-appearance for counts of 3-0 and 3-1. More walks lowered the defensive value of shifting. Data from Baseball Savant.

• 3-0 Increased walks-per-plate-appearance from .577 to .604.
• 3-1 Increased walks-per-plate-appearance from .769 to .778.

Considering wOBA for all pitch counts, Diamondbacks’ defensive shifting was most successful against the Dodgers, Athletics, and Giants. It was least successful against the Astros and Angels. For details see the table.

Considering all pitch counts, shifting against the Dodgers was successful for four reasons:

• Reduced wOBA from .330 to .320.
• Reduced homers-per-plate-appearance from .047 to .044.
• Reduced walks-per-plate-appearance from .113 to .088. (Part of that was offset by reduced strikeouts which changed from .219 to .212.)
• Reduced pitches-per-plate-appearance from 3.86 to 3.70.