Left-hander Julio Urias starts for the Dodgers tonight in Game 4 of the NLCS against the Cubs. Here’s something you probably already know about him: he’s really young. Urias turned 20 on August 12 of this year. For the purposes of websites such as this one (which use July 1 as a cutoff), that places Urias in the midst of his age-19 season. When Urias pitched in relief during Game 5 of the NLDS, he became the fourth-youngest pitcher in major-league history (Bert Blyleven, Ken Brett, Don Gullett) to pitch in the postseason, per Baseball-Reference Play Index — and he’s already pitched more innings than Brett and as many as Blyleven. With his first pitch today, he’ll become the youngest pitcher in postseason history to record a start. By comparison, consider that most of the players on both the Cubs and Dodgers had never even appeared in a professional game at the same age Urias ascends to the spotlight.

Only seven players in history have started a playoff game at an age younger than Urias, and they were all position players. They are, in declining order of age at playoff debut: Justin Upton, Claudell Washington, Bryce Harper, Mickey Mantle, Andruw Jones, Phil Cavarretta, and Freddie Lindstrom.

That’s one way to frame Urias’s accomplishment. Another? By means of this brief timeline concerning the distinction Urias is about to receive:

On October 9, 1913, Bullet Joe Bush started for the Philadelphia Athletics in the third game of the World Series. he pitched a complete game as the A’s beat the New York Giants 8-2. Bush was 20 years and 316 days old. Bush would hold the record until…

October 3, 1984, when Bret Saberhagen started for the Kansas City Royals in Game 2 of the ALCS against the Detroit Tigers. The Tigers won 5-3. Saberhagen was 20 years and 175 days old.

Urias is 20 years and 68 days old today.

Urias’s age is not remarkable solely for how it relates to his postseason appearance and playoff start. His regular-season performance this year, even in limited innings, represents one of the better seasons in history for a player his age. In 77 innings this season, Urias put up a 3.39 ERA and 3.17 FIP, which was good enough to produce a 1.8 WAR. Over the last 40 years, only seven players, position players included, have recorded a better WAR number in a season at 19 years of age or younger:

Best Age-19 and Under Seasons Since 1967 Season Name Team WAR 1984 Dwight Gooden Mets 8.3 1967 Gary Nolan Reds 5.3 2012 Bryce Harper Nationals 4.6 1970 Bert Blyleven Twins 3.6 1996 Edgar Renteria Marlins 3.5 1989 Ken Griffey Jr. Mariners 2.5 2005 Felix Hernandez Mariners 2.3 2016 Julio Urias Dodgers 1.8

That list is cut off with Urias, but there are only two other players with a WAR even exceeding 1.0: Manny Machado and Rick Ankiel. Even going back 100 years, the only position players to recorded more than 1.8 WAR were Hall of Famers Mel Ott and Travis Jackson — as well as Buddy Lewis and Tony Conigliaro. Another seven pitchers have exceeded 1.8 WAR, including Bob Feller and Milt Pappas. It’s possible that, when we think of Urias’s age, we sort of shut things down at a certain point and consider young as young, not considering the difference between age 19 and age 20. In reality, however, even that single year separates makes a difference. Consider: over the last 20 seasons, 36 different 20-year-olds have pitched in the majors. Only seven pitchers — Hernandez, Urias, Ankiel, Edwin Jackson, Dylan Bundy, Madison Bumgarner, and Matt Riley (in order of WAR) — have recorded a pitch in their age-19 seasons.

To provide some perspective, let’s take a look at what Urias’s teammates were doing during their own age-19 seasons. The graphs below depict the number of players at each level for the current Dodgers 25-man roster. (A full table of the relevant information appears at the bottom of the post.)

Thirteen of the Dodgers on the NLCS roster hadn’t yet made a professional appearance yet, while Rich Hill was still in high school and Carlos Ruiz had yet to be signed by Philadelphia Phillies out of Panama. Kenta Maeda had yet to make his debut in Japan’s top league, while Yasiel Puig was in his second professional season in Cuba. Only two players had even made it past Low-A, a level still four rungs below the majors. Corey Seager made it to High-A, playing in 27 games there after spending the bulk of the year in Low-A, and Clayton Kershaw made five starts in Double-A after spending the bulk of the season in Low-A.

The graph below shows how far from the majors the current Dodgers were at age 19.

All but Seager and Kershaw were at least three years from the majors when they were Urias’s age. The average age of the Dodgers’ debuts is 24 years old, five years older than Urias. Joc Pederson, a rookie last year, is five years older than Urias. Pederson and Urias are as far apart in age as Urias and an eighth-grader.

Now let’s compare Urias to his opponents in the NLCS, the Chicago Cubs. The Cubs have a reputation as a younger team, so maybe his youth won’t seem so out of place.

First, here are the levels at which the Cubs’ 25 players were played during their age-19 seasons:

We can see that the Cubs players, at least in terms of where they were as prospects, were a little more advanced than the Dodgers were. At 19, five players appeared at High-A or above. That said, the presence of two players at Triple-A is slightly deceiving: Addison Russell played the entire year at High-A before getting three games in at Triple-A and then spent most of the next season in Double-A. Jason Heyward, meanwhile, also only played three games at that level after splitting most of the season between High-A and Double-A. He did start the next season in the majors, though, which is something.

Here’s how far the Cubs players were from the majors at age 19.

Pedro Strop of the Cubs and Kenley Jansen of the Dodgers were still position players at 19 years old, having not yet made the transition to the mound. It took an average of four more years past age 19 for Cubs players to reach the majors.

When we combine the two teams to see where all 50 players were at age 19, the graph looks like this:

In the postseason, the word history gets thrown out a lot. Players and teams are constantly accomplishing feats that are rare and worth mentioning for their context in the game’s great past. That’s part of what makes the postseason great.

Urias has accomplished a number of such feats already and is about to accomplish at least another one. In the past 100 years, only two players have been able to say they were the youngest pitcher in playoff history to make a start. Later today, Julio Urias will become the third and only he will be able to make that claim for the foreseeable future.

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As noted above, here’s the full list of NLCS players below (chart is sortable):