Walker Buehler's breakout hasn't stopped. Why would it? He's got high-90s heat, two wipeout breaking balls, a cutter he's taken to the next level, and command of the whole package. The Dodgers' 25-year-old ace-in-the-making enters Friday's start with 152 strikeouts this season; he's walked only 20. He leads the Majors

Walker Buehler 's breakout hasn't stopped. Why would it? He's got high-90s heat, two wipeout breaking balls, a cutter he's taken to the next level, and command of the whole package.

The Dodgers' 25-year-old ace-in-the-making enters Friday's start with 152 strikeouts this season; he's walked only 20. He leads the Majors in strikeout-to-walk ratio at 7.60. It's Clayton Kershaw-like, from the pitcher who may one day take up Kershaw's mantle in Los Angeles.

Buehler has already delivered a pair of the 2019 season's biggest gems: two starts with 15-plus strikeouts and zero walks, a feat only Pedro Martinez (in 1999 and 2000) and Dwight Gooden (in 1984) have achieved twice in a year.

Here's how he's doing it.

GETTING THE K'S

Buehler is throwing more four-seamers.

Stop us if this sounds familiar (Hi, Astros!). Buehler has mostly pocketed his two-seam fastball in favor of four-seamers.

This season, he's throwing 54.4% four-seam fastballs and just 6.6% two-seamers. Last year, when he moved into the Dodgers' rotation, Buehler was using much more of a mix: 40.8% four-seamers and 18.8% two-seamers.

It's not that his two-seamer is ineffective; it's actually gotten excellent results, too, like most of what he throws. But the four-seamer is more of a strikeout pitch, especially when it's the high-velocity, high-spin variety at Buehler's fingertips. (He has a 96.6 mph average velo and 2,440 rpm average spin rate ... MLB average is 93.4 mph and 2,286 rpm.) Buehler's four-seamer gets +2.3 inches of "rise" above average. His two-seamer doesn't have nearly as much movement.

Buehler has recorded 71 of his 152 strikeouts on four-seam fastballs in 2019. But his secondary stuff is better, too.

Buehler's breaking balls are sharper.

Buehler has added over 100 rpm of spin on both his curveball and slider. His curveball spin rate has increased from 2,757 rpm in 2018 to 2,892 rpm in '19 -- higher than over 90% of the league (MLB average curveball spin is 2,521 rpm). His slider spin rate has increased from 2,761 rpm to 2,862 rpm.

Both pitches are moving more. On his curveball, Buehler has added about an inch more of both horizontal and vertical movement relative to average. On his slider, he's added about two inches in both horizontal and vertical movement relative to average.

The swings-and-misses, chases out of the strike zone and strikeout numbers have shot up on both pitches. That sure doesn't look like an accident.

Those same metrics have improved in kind on his cutter, even with little difference in its shape. Buehler's swing-and-miss rate on his cutter has leaped from 18.2% to 26.0%, his chase rate from 23.0% to 40.3%, and his strikeout rate from 12.5% to 22.6%. Those are major increases on an already-wicked pitch that sits in the low-to-mid-90s with movement. And it might be a ripple effect from the change in the breaking pitches.

Walker Buehler, 94mph Cutter and 90mph Back Foot Slider, Overlay. pic.twitter.com/ALnAtClYdc — Rob Friedman (@PitchingNinja) May 25, 2019

PREVENTING WALKS

Buehler is working ahead.

Barely one in five pitches Buehler has thrown this season have been with him behind in the count. He's cut that number each year, from 29.2% of his pitches as a September callup in 2017 to 23.7% of his pitches last season, to 21.9% of his pitches this season.

In fact, Buehler gets ahead of hitters at one of the highest rates in baseball. Over a third of his pitches thrown have been while he's ahead in the count, ranking third in MLB among regular starters. You're not going to walk many guys if you follow that recipe.

Highest % of pitches thrown while ahead in the count, 2019

Min. 1,500 total pitches (104 pitchers)

1) Chris Paddack (SD): 37.4%

2) Max Scherzer (WSH): 36.8%

3) Walker Buehler (LAD): 34.2%

4) Jose Berrios (MIN): 34.0%

5) Gerrit Cole (HOU): 33.9%

Buehler's simplified his repertoire.

Buehler has also tightened up his pitch selection in different types of counts.

When he does fall behind now, he uses his four-seamer to get back into the count, or sometimes his cutter, which has become more of a weapon for him (13.4% usage, compared to 7.7% in 2018). Last year, Buehler's pitch types were more spread out across his arsenal even when he was behind.

And when he gets ahead, he buries hitters with his two breaking balls -- without forgetting about his overpowering four-seamer, of course. Buehler's curve, slider and primary heater have made up a heavier share of what he throws in those putaway two-strike counts.

Buehler right now is averaging double-digit strikeouts per nine innings (10.42), and he's got more games started than free passes issued (21 to 20). Only two qualified started have ever matched that in a season: Curt Schilling for the D-backs in 2002 (35 starts, 33 walks, 10.97 K/9) and Ben Sheets for the Brewers in 2004 (34 starts, 32 walks, 10.03 K/9).

You don't get numbers like those without serious stuff and sharp execution. Buehler is harnessing some of the best stuff in the game. He's a star.