MLB Pitch Clock 2023: How Did It Impact Game Outcomes?

photo courtesy: CNN

Say what you want about the MLB pitch clock and the new rules this past season. The desired effect--to shorten the game--was achieved.

Time of MLB games dropped 

Pace of play (time in between pitches has also dropped)

What about the game itself? 

Larger bases and limited throws to first base with a runner on strongly suggested stolen bases success rates would be higher.  

Shift elimination helped bring the balls in play batting average (BABIP) for left handed hitters in line with right handed hitters.

Weighted on base average (wOBA) also rose.

All of these changes were expected as a result of the rule changes and the addition of the pitch clock. Yet many aspects of the game such as balls in play and the high strikeout totals -- to name a few --remained pretty much the same. 

The 16 charts below illustrate how the core of the game has changed over the last 15 years or so.

Three plate outcomes (walk, strikeout, homerun) rates have been rising since roughly 2010 peaking in 2020 with a small drop in 2021 and 2022 with a jump in 2023 AFTER the rule changes.

Rate of balls in play started a sharp decline in the late 2000s hitting a low of 67.3% in 2020. A small increase in the last 3 years but no where to the 1990s/early 2000s levels.

Strikeout rates saw a similar rise at roughly the same time. Again little change last season.

Swing strike percentages have hovered around 19% over the last 5 seasons. The increase started around 2010.

The percentage of pitches swung at outside the strike zone started rising in the mid/late 2000s. Rates at 18.1% in 2002, 21.5% in 2005 jumping to near 30% by 2010 where they've stayed ever since.

Contact on pitches outside the strike zone also way up starting in the late 2000s with the rate steady since 2010.

Percentage of pitches inside the zone dropped at roughly the same time.

Flyball rates have rose since early 2010s lows back to early 2000s levels,

Home run rates per plate appearance stayed the same until roughly 2015 then a 35% jump between 2015 and 2019. HR per plate appearances have remained elevated since.

As home run rates rose, slugging percentage on flyballs also rose through 2019. Since then, then have dropped to early 2010s levels.

Percentage of runs via home runs rose in 2023. Overall levels remain at 2016 levels.

Slugging percentage AFTER 2 strikes started falling in the late 2000s. A few brief jumps but nothing sustainable.  Average "After 2 strike slugging" remains steady over the last decade.

Interesting to note that slugging with runners in scoring position, after a drop between 2006 and 2014, has jumped back to mid 1990s levels.

On top of of offensive changes over the last 10-15 years, pitching speed and frequency has shifted. Velocities are higher across the board.  

Fastball frequency is down more than 12%.  Sliders are up almost 8%. Cutters are up 5% versus a decade ago.  However curveballs and changeups are unchanged.

All of this data points to system wide changes to how game actions are executed. These changes have occurred over almost a full generation.  As of this writing, the 2023 rule changes/pitch clock additions changed base running and defensive alignments. Yet players' approach at the plate and the way pitchers pitch remains so far unchanged. The game is faster, pace of play is down yet the type of baseball we've been watching in recent years remains the same.  Will this change in the next 5 -10 years? 

Winter 2022-23 Recap - Part III - The Drivers

Part I and II recapped the temperatures and snowfall for last winter. Why did these temperatures and snowfall occur?  What were the individual drivers of each period last winter?  I am sure I will miss some features in this long post so let me know.  We start in October with our first snowfall of the season.

Strong cold front with a ton of vorticity spun up over the Great Lakes.  Temperatures at 1000 feet off the ground (850 mB level) dropped to between -4 and -6 the night of October 18th.

Vorticity 

850 mB temperatures

500 mB height anomalies were extremely low and deep

500 mB height anomalies

Cold temperatures were widespread across the central US and Ohio Valley

This resulted in light accumulations across the eastern 1/2 of northern Ohio

By November, the pattern became more variable.  First 10 days of the month featured well above normal temperatures followed by a sharp cold spell then another milder stretch around Thanksgiving.

The pattern across the country was about as polar opposite west to east as it can get during the first half of November. HUGE ridge and warmth across the east, trough and cold west

The pattern flipped the second half of the month. 

The first week of November was incredibly warm and snow free.  By the middle of the month, temperatures averaged in the 30s for 10 straight days with frequent snowfall.

The last 7 days of November temperatures moderated.  Snowfall was sporatic

Around Thanksgiving, there were indications that the middle/third week of December was trending MUCH colder than normal and the cold would be fairly widespread. A precursor to the extreme cold which invaded the central US the week of Christmas.  My tweet on November 22 indicated this. The duration and day-to-day intensity of the cold was not known at that time. 

December 12 projections started picking up on the Christmas cold.

By December 14, I drew up long range model comparisons to the December 25th cold in 2000.

By December 19, the cold signal for Christmas week was very strong stretching across the continent.

Our forecast 5 days before the cold!

Cold extended into central Florida

Progression of the cold across the central US

Snowfall forecast for northern Ohio

Wave height on Lake Erie

December temperatures were overall below normal with a quick rise by New Years Day.

The ridge in the Pacific shifted north of the Arctic Circle. Trough developed across the Great Lakes and then the COLD. Strong Greenland ridge developed.

The Northern Atlantic and Arctic pressure pattern were strongly negative as the Greenland ridge strengthened. (Blue bars below)

Arctic Oscillation Phases

North Atlantic Oscillation Phases

The Greenland block historically correlates to colder temperatures across the eastern US. This matched up with late December.

By January, a HUGE northern Pacific ridge developed locking in a milder pattern across the eastern US

The polar vortex rapidly strengthened in January.  By early January, the pattern was showing signs of what we experienced in November. Fast moving systems with frequent changes in the temperature with little extreme cold. 

Greenland Block (ridge circled in black) weakened for most of January and February.  NAO shot up.

Temperatures across much of eastern North America and US went well above normal.  Here is the progression from late December through February.

Overall temperature ranks over the two month period were top 5 across much of the eastern US.

January temperatures vs normal for Cleveland.  Notice most days were in the 40s and 50s.

February temperatures vs normal for Cleveland.  More 50s and a few 60s.

December through February were some of the cloudiest winter periods on record for parts of the Great Lakes and New England. H/T Brian Brettschneider

However, by March the Greenland Block resurfaced.

The Madden Julian Oscillation (MJO) quickly migrated into phases 7, 8 and 1 with off-the-charts magnitude. The forecast was indicating this in late February.

Actual MJO verified just as strong.  These tropical changes strongly hinted at a colder March eastern US with an active storm track.

MJO phase and magnitude in March

In summary, the colder March pattern shift was the result of many factors? First since mid/late February, the temperatures in the upper atmosphere had been warming over the North pole. The sudden warming in the stratosphere over the pole translates to high pressure over the north pole at the surface with colder temperatures and often a weaker polar vortex. (

Great graphic below showing the warming in the upper atmosphere from November through March. As the polar vortex weakened, the displacement propagated down into the lower atmosphere first in late December. It rapidly strengthened in January. Then a late February warming with a downward propagation in March and again in late April

Polar Vortex Behavior from Nov to April (red indicates weakening--colder)

These changes high in the atmosphere over the pole propagate to the lower levels and further south into the tropical regions. These changes intensified the MJO (Madden Julian Oscillation) as it transitions out of warmer phases (2-3-4 much of the winter) to colder phases (8-7-1). (see MJO images above)  The jet stream responded with more variability off of eastern Asia east over the northern Pacific and into North America.  This has resulted in high pressure developing near Alaska and low pressure undercutting north of Hawaii.  Greenland high pressure which reinforced the undercutting storm track strengthening the jet stream and the trough as it moved east into the Ohio Valley along with colder air.  

Overall March temperatures vs normal.  Notice little relative warmth.

All of this occurring in a slowly decaying La Nina along the equatorial Pacific. Blue colors (cooler water)

If this late season pattern shift would have occurred 6 weeks earlier, our winter would have been MUCH different:  COLD and more SNOW in January and February.