Julio Urias, a 16-year-old left-handed pitcher from Mexico, made his professional debut with the Great Lakes Loons today.

It was an aggressive assignment by the Los Angeles Dodgers — players that young are far more likely to be in the Dominican Summer League or a rookie-level or short-season league than the Low-A Midwest League — but it appeared to be the right move, at least today. Urias went three innings, giving up only two hits, one walk and no runs while striking out six. According to MiLB.com, 35 of his 52 pitches were strikes. Loons play-by-play broadcaster Jared Sandler reported that Urias showed a good mix of pitches and reached 94 mph with his fastball.

The Loons lost the game to the Dayton Dragons in 12 innings. Junior Arias doubled, stole third base and scored the winning run on a ground out by Jeff Gelalich. But those are just side notes to the big story that was a 16-year-old pitching in the Midwest League. (Read the MiLB.com story about Urias’ debut here.)

So what do we know about Urias? I admit I hadn’t heard of him before reading he would start for the Loons today, so I had to do some research. Fortunately I was able to find some information about him, including this from today’s Loons Game Notes:

Highly sought-after left-handed international prospect … Rated by Feelinkindablue.com as the Dodgers’ #26 prospect: “Aside from Yasiel Puig and Hyun-Jin Ryu, Urias was the most noteworthy 2012 international signing the Dodgers made … It’s difficult to project such a young prospect, but when he already has a legitimate two-pitch repertoire, it makes it a little easier … Fastball that sits in the upper-80s and has touched 92 MPH. He can cut it. His upper-70s changeup is what has scouts raving.”… From Ben Badler, Baseball America: “Changeup is a potential plus-plus pitch … good delivery and a loose arm … he’s able to cut his fastball and throw it for strikes … His changeup is one of the best secondary pitches in this year’s class, throwing the pitch in the high-70s and earning plus to plus-plus future grades from scouts.”

The game notes also said Urias was born with a tumor in his left eye that required corrective surgery, and that he hails from Culiacan, Mexico, home of Seattle Mariners LHP Oliver Perez. (Incidentally, Perez pitched for the 2001 Fort Wayne Wizards. The then-19-year-old went 8-5 with a 3.46 ERA and 98 strikeouts in 101.1 IP.)

It will be interesting to see how Urias performs in subsequent outings.

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Throughout the day I tried (with help from others) to find out when the last time a 16-year-old played in the Midwest League. It was not an easy task, as many minor-league statistics such as this can be difficult to find.

Hardball Times analyst/writer Brian Cartwright was able to trace back to 1998, finding that three 17-year-olds have pitched in the MWL since then, including Felix Hernandez in two games with the Wisconsin Timber Rattlers in 2003. RedsMinorLeagues.com writer Doug Gray looked back further on Baseball Reference, finding no 16-year-old Midwest Leaguers as far back as 1990. I took a stab by asking Elias Sports Bureau, but was told they don’t have that kind of data at hand.

Fellow Midwest League enthusiast David Malamut came through by asking Joel Dinda of A Fan’s Guide to the Midwest League. Dinda found four possibilities in his database, and Malamut checked them on Baseball Reference. Although BR is not always perfect when it comes to ages, it revealed that at least two 15-year-olds apparently pitched in the Midwest League: RHP Mike Jones in three games with the 1961 Keokuk Cardinals, and RHP Cedric Wolfman in 16 games with the 1954 Clinton Pirates. (That Clinton team actually was in the Mississippi-Ohio Valley League, a predecessor league whose records and statistics are considered part of the Midwest League recordbook.)

My thanks to all the men listed above for their varied degrees of help looking for this information, and to Baseball Prospectus contributor Harry Pavlidis for his original query about it on Twitter. I hope that this long-winded explanation helped shed some light onto the type of process that sometimes takes place when looking for old minor-league information.