The secret to Acuña's historic basestealing

There's no better figurehead for the 2023 stolen-base movement than Ronald Acuña Jr.

With the new rules creating more freedom of movement on the bases -- pickoff limits, the pitch timer and bigger bases -- no one is taking advantage like the Braves' electric superstar.

After 100 games, Acuña leads the Majors with 48 stolen bases. He's on pace for 78 steals, which would be the first 70-steal season since Jacoby Ellsbury in 2009. And that's before you even get into his 37-homer pace and how he could make power-speed history.

But this is about the steals. There are five key steps to Acuña's stolen-base success. Let's break down Acuña's season -- and how the new rules are powering it.

Here's how Acuña became the face of the stolen base in 2023.

1) He creates lots of chances to run … and takes them

Step 1 of stealing a base is _getting on base_, and Acuña, batting .327 with a .407 on-base percentage as the Braves' leadoff man, gets on base more often than nearly anyone else. Only Freddie Freeman and Juan Soto have reached base more times this season, and they're hardly the burners Acuña is.

All those times on base translate to a lot of chances to steal. Acuña ranks in the top 10 in the Majors in stolen-base opportunities -- that's when he's on first or second, with the next base open in front of him.

Most stolen-base opportunities, 2023

• Steven Kwan: 236
• Freddie Freeman: 222
• Luis Arraez: 218
• Juan Soto: 218
• Christian Yelich: 217
• Paul Goldschmidt: 217
• Marcus Semien: 214
• Ronald Acuña Jr: 212
• Nico Hoerner: 212
• Bo Bichette: 211

Of course, having the opportunities to steal doesn't mean anything if you don't have the speed and aggressiveness to seize them. And in this new stolen-base environment, Acuña is seizing them like never before.

Acuña has 56 steal attempts in his 212 opportunities. He runs over one in every four times he has the chance. That's one of the highest rates in the league -- four times as often as the average MLB player -- and the highest rate of his career.

Most SB attempts per opportunity, 2023
Of 191 players with 100+ opportunities

1. Esteury Ruiz: 50.5%
2. Willi Castro: 27.9%
3. Bobby Witt Jr.: 26.9%
4. Ronald Acuña Jr.: 26.4%
5. Wander Franco: 25.9%
6. Corbin Carroll: 24.8%
   MLB average: 6.5%

Acuña's SB attempts per opportunity by season
2018: 10.5%
2019: 18.0%
2020: 10.2%
2021: 15.3%
2022: 19.1%
2023: 26.5%

What's different about 2023? It's actually not Acuña's speed (more on that in a second). It's the state of the game around him. That's what has set the stage for his 48 stolen bases.

2) He has the basestealing aggressiveness of a 20-year-old rookie again

Now let's dive into Acuña's Statcast data. We can use Statcast to look at the two main components of his stolen bases: his leads and his speeds.

Here's what might surprise you: Acuña doesn't really stand out from other basestealers in terms of getting big jumps, or swiping bags with elite speed.

Let's focus on steal attempts of second base, since there are a lot more of those, and it's an easier standard to analyze basestealing. Acuña has attempted 43 steals of second this season. On those attempts, his average primary lead distance (when the pitcher starts his delivery) is 11.5 feet. His average secondary lead distance (when the pitcher releases the pitch) is 22.3 feet. His 50th percentile sprint speed is 28.5 ft/sec.

Those are fairly typical leads for a big league runner, and while Acuña's speed on his stolen bases is certainly very good (MLB average sprint speed is 27 ft/sec), it's not at the elite end (30-plus ft/sec).

But there is a big difference within Acuña's own metrics. While his speed has leveled off, he's taking significantly bigger leads in 2023 compared to previous seasons.

Acuña is a bolder basestealer right now than he's been since his rookie season, when he was a 20-year-old at peak speed who was taking the league by storm.

Acuña's leads on SB attempts of 2B, by season
2018: 12.0 foot primary, 23.3 foot secondary
2019: 10.4 foot primary, 22.2 foot secondary
2020: 11.4 foot primary, 21.7 foot secondary
2021: 9.7 foot primary, 20.6 foot secondary
2022: 10.0 foot primary, 21.4 foot secondary
2023: 11.5 foot primary, 22.3 foot secondary

With the pickoff limits and pitch timer in 2023, Acuña is testing pitchers much more than he did in 2021 and '22. His leads are almost two full feet bigger than they were just two years ago.

He's putting himself in position to steal bases en masse, even though his pure speed isn't as high as in seasons past.

Acuña's max sprint speed on a steal attempt of second base this season is 29.0 ft/sec, a mark many top basestealers will eclipse. But he's reached 28 ft/sec or faster on 22 different successful steals. Only five other players have even stolen second base 22 times, period, at any speed -- Esteury Ruiz, Bobby Witt Jr., Wander Franco, Starling Marte and Corbin Carroll.

With Acuña's newfound aggressiveness in leading, that approach of bulk steals at solid speed is paying off.

3) Pitchers are risking valuable stepoffs to stop him

Pickoff attempts are at a premium now that the rules have changed. With the two-disengagement limit, not only does each stepoff from the rubber bring the pitcher one step closer to an automatic balk, it also brings an increased risk of the runner taking a bigger lead and stealing.

Every time the pitcher steps off or throws over to first, the runner grows much more likely to steal second. Because the pitcher has less wiggle room remaining to hold him on.

When the pitcher has not yet stepped off, runners on first are stealing about once every 68 pitches. After one pickoff attempt, they steal every 17 pitches. After two pickoff attempts, they steal on over one in every 10 pitches.

Stepping off the rubber has become a double-edged sword. It's still a critical tactic in controlling the run game, but the risk of a stolen base rises every time you do it.

But with Acuña, pitchers are desperate to hold him on, even with the threat of him swiping the bag with ease if they fail to pick him off. They've stepped off or thrown over far more times against Acuña than any other baserunner this season.

Runners with most disengagements induced at 1B, 2023

• Ronald Acuña Jr. -- 73
• Nico Hoerner -- 55
• Christian Yelich -- 49
• Steven Kwan -- 49
• Randy Arozarena -- 47

Of course, Acuña's 37 successful steals of second base this season -- with only six caught stealings, an 86% success rate -- shows you how little those pitchers have really been able to do to prevent him from taking that bag.

4) Catchers are pushing themselves to the limit to catch him

Now we come to the last line of defense against Acuña: the catcher.

Catchers league-wide are feeling the squeeze. With their pitchers limited in how much they can control the run game, catchers are forced to go faster than ever before in an -- often futile -- effort to corral basestealers. Acuña is the perfect example.

Here's how catcher pop times to second base have changed across the league this season.

MLB avg. pop time to 2B by season
2016: 2.02 seconds
2017: 2.02 seconds
2018: 2.02 seconds
2019: 2.01 seconds
2020: 1.99 seconds
2021: 1.99 seconds
2022: 1.98 seconds
2023: 1.96 seconds

With stolen bases decided by fractions of a second, that's a big difference.

Catchers are being pressured into getting the ball down to second base as fast as they possibly can, even at the cost of accuracy. Statcast's Caught Stealing Above Average metric breaks down catcher throwing into each individual component, including accuracy, and this year, league-wide, catcher accuracy is the worst it's been in the Statcast era.

Acuña is the perfect example. Catchers have a 1.91 second pop time against him this season when he's stealing second base -- as fast as they've ever been against him in his career, and as fast as they've been against any runner in 2023.

Fastest catcher pop times by baserunner, 2023
Ronald Acuña Jr. -- 1.91 seconds
Randy Arozarena -- 1.91 seconds
Wander Franco -- 1.91 seconds
Owen Miller -- 1.91 seconds

Catcher pop time to 2B vs. Acuña by season
2018: 1.97 seconds
2019: 1.96 seconds
2020: 1.98 seconds
2021: 1.91 seconds
2022: 1.98 seconds
2023: 1.91 seconds

Like what's happening across the Majors, those catchers are also losing accuracy against Acuña as they prioritize a quick draw. The throw speed and release components of their Caught Stealing Above Average against him are a net positive, while their accuracy component is a negative.

But they really have no choice. Being faster is their only hope to catch a runner like Acuña.

The estimated caught-stealing percentage for a league-average catcher this season is 20%, already the lowest it's been in a season in the Statcast era. But with Acuña running, opposing catchers see their estimated caught-stealing percentage drop to 14%.

It's hard for even the best catchers to nab basestealers in 2023 -- the league's 80% stolen-base success rate is a historic pace. And Acuña is no ordinary basestealer.

5) Even with faster catchers, Acuña is stealing at will

Let's watch Acuña in action. Here he is stealing against five of the top catchers in baseball.

SB No. 48 vs. Connor Wong (July 25)

Start with Acuña's most recent stolen base -- against Wong, who's tied for the best among all MLB catchers with +7 Caught Stealing Above Average. Wong had an excellent 1.89 second pop time here, but Acuña got a good jump (24.7 foot secondary lead) and stole the base with a 28.0 ft/sec sprint speed.

SB No. 26 vs. Gabriel Moreno (June 4)

Moreno is the catcher tied with Wong atop the CSAA leaderboard. Here's Acuña stealing off him. Acuña's 24.0 foot secondary lead helped him beat Moreno's 1.94 second pop time.

SB No. 21 vs. J.T. Realmuto (May 25)

Realmuto is the king of pop time. Acuña still stole third against him, taking a big secondary lead of 32.8 feet and reaching a sprint speed of 28.6 ft/sec to beat Realmuto's 1.45 second pop time and give the Braves a double-steal.

SB No. 20 vs. Will Smith (May 23)

Smith couldn't do anything about this one, getting a good pitch to throw on and posting a 1.81 second pop time to second base. But Acuña reached a 28.8 ft/sec sprint speed and beat it.

SB No. 2 vs. Willson Contreras (April 4)

Contreras is one of the strongest-armed catchers in the game, and he put up the fastest pop time against Acuña this season here at 1.79 seconds. But he lost some accuracy on a short-hop, forced into it by Acuña's 25.4 foot secondary lead and 28.3 ft/sec sprint speed.

Acuña can steal against anybody, and he steals against everybody. He's a catcher's worst nightmare.

Statcast research for this story was provided by MLB's Tom Tango and Jason Bernard.