Thursday night at Minute Maid Park, Chicago White Sox right-hander Lucas Giolito turned in the best outing of his big-league career. Giolito held an Astros club with the highest batting average (.278), highest on-base percentage (.352), and second highest slugging percentage (.499) in baseball to four singles, one walk, and one hit-by-pitch in the shutout. He struck out nine.

Here's video of Giolito's masterful outing (CWS 4, HOU 0):

"He was really good. Hats off to him for coming in and throwing all his pitches for strikes," Astros manager A.J. Hinch told reporters, including MLB.com's Alyson Footer, following the game. "He's changed his delivery or his arm action a little bit, which got him in the strike zone. He generated a ton of swing and misses, soft contact. We got four hits. He came in and really commanded the game from the very beginning."  

By Game Score, Thursday's outing was easily the best start of Giolito's career. In fact, three of his four best starts have come this month. Here's the list:

DateResultIPHRERBBKHRGame Score

May 23, 2019 vs. Astros

4-0 W

9

4

00

1

9

0

87

May 7, 2019 vs. Indians

2-0 W

7 1/3

3

00

3

8

0

77

Sept. 3, 2017 vs. Rays

6-2 W

7

3

1

1

1

10

1

76

May 12, 2019 vs. Blue Jays

5-1 W

7

4

1

1

1

8

0

72

A year ago Giolito, who is still only 24, was one of the worst pitchers in baseball. He led MLB in earned runs allowed (118) and the American League in walks (90), and finished the season with a 6.13 ERA in 173 1/3 innings. Giolito became the first pitcher to throw enough innings to qualify for the ERA title and finish with an ERA north of 6.00 since Brandon Backe (6.05), Livan Hernandez (6.05), and Nate Robertson (6.35) all did it in 2008.

This season Giolito has been among the very best pitchers in baseball. Following Thursday's shutout in Houston, he owns a 2.77 ERA in nine starts and 52 innings, and he ranks among the American League's top 10 in basically every meaningful pitching category:

  • ERA: 2.77 (8th)
  • ERA+: 161 (8th)
  • FIP: 2.78 (3rd)
  • K/9: 10.2 (9th)
  • WHIP: 1.06 (8th)
  • WAR: 1.8 (4th)

Giolito is not an out-of-nowhere success story. He was arguably the top prospect in the 2012 draft class before slipping to the Nationals and the 16th overall pick due to elbow concerns. (Sure enough, Giolito had Tommy John surgery shortly thereafter.) Four times Baseball America ranked him among the game's 25 best prospects (2014-17). Washington sent Giolito to the White Sox as the headliner in the Adam Eaton trade three years ago.

Last year Giolito looked like a bust. He really did. This year he looks like the pitcher who sat near the top of all those prospect lists, and there are two key reasons why Giolito has been able to turn his career around. First of all, he stopped throwing his sinker and embraced elevated four-seam fastballs. Elevated four-seamers are a wonderful swing-and-miss pitch, and they are seemingly more effective than ever in the launch angle era.

Lucas Giolito has completely stopped throwing his sinker this season, and is instead emphasizing his four-seam fastball. Brooks Baseball

"We're pretty into all that stuff now as far as Trackman and all those amounts and numbers," Giolito told The Athletic's James Fegan recently, and the numbers back it up. Opponents hit .284 and slugged .461 with a 5.5 percent swing-and-miss rate against Giolito's sinker last year. This year they're hitting .258 with an .371 slugging percentage and a 8.9 percent swing-and-miss rate against the four-seamer.

The other adjustment Giolito made this season is a bit more subtle than pitch selection. He changed his position on the mound. Specifically, Giolito has moved to the first base side of the pitching rubber. Here are the before and after screengrabs:

Lucas Giolito has moved to the first base side of the rubber in 2019. MLB.com/CBS Sports

Rays lefty Blake Snell changed his position on the rubber in the middle of the 2017 season, and it helped turn him into a Cy Young winner. Jake Arrieta changed his position on the rubber with Cubs in 2014, and a year later he was a Cy Young winner. Those are extreme examples, obviously. I wouldn't pencil Giolito in for a Cy Young just yet. But they show that a simple change in mound position -- moving on the rubber changes all the pitcher's angles -- can lead to huge results.

I suspect Giolito has some home run rate regression coming -- pairing a 0.52 HR/9 with a 37.0 percent ground ball rate long-term seems unsustainable in the launch angle era (and in that home ballpark) -- but the overall improvement is real. He's missing more bats, doing a better job limiting walks, and not giving up as much loud contact. Shelving the sinker and emphasizing the four-seamer, and the shift on the rubber are tangible reasons to believe in the new and improved Giolito.

Develop is not linear. Snell and Arrieta are two pretty great examples of that. It can take young players time to figure things out at the big league level, even the most talented young players, but once they do figure it out, the improvement can be rapid. Giolito endured a brutal season last year. To his credit, he learned from that experience, made some changes, and is now emerging as one of the top starters in baseball.