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Baltimore Orioles

How might the Orioles’ changes at Camden Yards affect the number of home runs? Here’s what we found. | ANALYSIS

Of the changes that have happened throughout the Orioles organization over the past handful of years, perhaps none is as certain to be long-lasting as the team’s decision to alter the left-field dimensions at Camden Yards. But for several reasons — “everything from the ball that Major League Baseball decides that we’re going to use to global warming,” as Orioles assistant general manager for analytics Sig Mejdal put it — the magnitude of that future impact is hard to measure in the present.

The same thought doesn’t quite apply to the past. Using data from MLB’s Statcast tracking system and an online plotting of home runs since its introduction in 2015, The Baltimore Sun determined that at least 14% of the home runs hit at Camden Yards in those seven seasons would have stayed in play with the ballpark’s new layout.

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The changes, which The Sun first reported earlier this month, will see the wall from the left-field corner up to the bullpens in left-center field — an area representing about a third of the stadium’s fair territory — moved back by as much as almost 30 feet, with the wall’s height increasing by more than 5 feet as a result of the portion of the seating bowl being removed. Although the left-field corner is staying 333 feet from home plate, the wall’s distance quickly increases by more than 50 feet in that area, the farthest any ballpark’s wall is from home plate that close to the left-field foul pole.

Although The Sun can’t fast-forward through next season to measure the impact of the adjustments, we can use publicly available data from the past several years to see how it might have affected games at Camden Yards.

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Methodology

Before we get into the math, let’s get into some math. Since 2015, there have been 1,581 home runs hit at Camden Yards, the most of any ballpark by a significant number, according to Baseball-Reference. Of course, not all of those were hit to the portion being altered.

Using the search feature on Baseball Savant, MLB’s public hub for Statcast data, The Sun downloaded information on all 1,581 home runs, eventually reducing that list to 640 home runs hit to the left-third of the field that had details available about their direction and distance. Of the 62 home runs removed from the data for lacking landing coordinates or projected distances, exactly half featured a description saying they went to left or left-center field. We counted another 22 home runs that landed in the bullpens, which will be unaffected by the construction, leaving us with a final tally of 618 fully tracked home runs to the altered area, or about 39% of those hit at Camden Yards during that time.

Andrew Perpetua, founder of advanced metrics site xStats, shared a plotting of each home run hit that direction since 2015, showing where they landed relative to the old and new dimensions. Perpetua’s charting features 649 home runs, including the balls that distinctly landed in the bullpen and nine more for which Statcast did not have direction data available.

The Sun determined the home runs’ directions by calculating a “landing angle” using the hit coordinate values provided by Baseball Savant. The calculated landing angle is different than Baseball Savant’s launch direction metric, which is effectively the lateral version of the more commonly used launch angle, in that it’s about how the ball is struck rather than where it lands. Because of weather and the natural slice left- and right-handed hitters oppositely put on batted balls, two home runs can have widely different launch directions but the same landing angle, and vice versa.

Perpetua found that a landing angle of about minus-15 degrees represented the cutoff of the dimension changes, where minus-45 represents the left-field line, 45 the right-field line and 0 dead center. Using this same cutoff brought The Sun’s list to 640 home runs, and thanks to Baseball Savant having broadcast video available for each home run beginning in 2016, The Sun then determined the number of home runs that clearly landed in either team’s bullpen.

By eye, Perpetua grouped the home runs into “Kept,” “Lost” and “Maybe” factions to describe whether they remained home runs. The Sun repeated this process, hedging slightly more by categorizing them as “Likely,” “Doubtful” and “Questionable,” in some cases — particularly near the bullpen and left-field corner — while reviewing video of the home runs. A handful of Perpetua’s plottings differed from those on Statcast, which was taken into consideration as The Sun evaluated those home runs.

Ballpark impact

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Orioles executive vice president and general manager Mike Elias said last week the alterations are to reduce the ballpark’s home run-per-flyball rate “more towards the league norms.” Since 2015, 19% of all flyballs hit at Camden Yards have sailed over the fence, per Statcast, the highest of any regularly used venue. League average in that metric during that time was 16%, a difference from Camden Yards’ rate of about one fewer homer per 33 flyballs.

Based on the number of flyballs hit at Oriole Park during this seven-season span, that level of reduction would result in 30 fewer home runs a season in a traditional 81-game home schedule. That number averaged across seven seasons, however, comes in beneath The Sun’s count of 227 home runs that would have been doubtful to stay in under the new dimensions.

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That’s nearly 35% of the tracked home runs between the left-field corner and the bullpens, and 13.5% of the total hit at Camden Yards over the past seven seasons. The proportion increases to just above 14% when considering only the total count of home runs for which coordinates and distance were available. Dropping 227 home runs would take Camden Yards from the most homer-prone ballpark of the past seven seasons to fourth.

The Sun took a cautious approach to classifying the home runs, meaning it’s possible a good chunk of the “Questionable” group (and possibly some of those deemed “Likely”) also would no longer be home runs. If even half of the balls the Sun considered questionable would have stayed in play, home runs at Camden Yards would have dropped by about 18%, with a 46% percent reduction in that area of the park. The Orioles’ home park would drop to the 10th-most home runs allowed since 2015, but only 10 ahead of 13th place.

If all questionable homers would have stayed in, that would account for almost 57% of the home runs hit to the left third of Camden Yards. That’s an overall drop of about 23% for the ballpark, which would then be 14th in home runs allowed, much in line with Elias’ hope of being in the middle of the league.

Although the Orioles are performing this change to make Camden Yards less home run friendly, they expect it to remain a hitter’s park. Regardless of what percentage drop the new dimensions will cause, not all of these balls in play would go from being home runs to outs. The teams hope the alterations lead to more exciting baseball at Camden Yards, with that area promoting an increase in non-homer extra-base hits. Given that most of this seven-year period has featured losing Orioles teams, increased excitement at Camden Yards should be most welcome.

“I do think that this might encourage a more exciting, athletic style of play in this part of the park,” Elias said last week. “We will have some additional extra-base hits, possibly triples, balls rattling around. I think it’ll be very fun and interesting. It’s something baseball in general needs more of, and I think it will ultimately improve the aesthetic style of play at Camden Yards from a number of angles. We’re looking forward to that.”


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