Julio Urias opens 2016 in Triple-A Oklahoma City starting rotation

SAN DIEGO -- Julio Urias will open the season in the starting rotation with the Triple-A Oklahoma City Dodgers, who officially announced their opening day roster on Wednesday. However, what might be more notable is who isn't in Triple-A, at least not yet.

Urias, the Dodgers' top pitching prospect and one of the top 4-6 overall prospects in baseball, doesn't turn 20 until August, but he will open the year in the OKC rotation.  Urias, who threw just 80 innings in 2015, is the fifth starter for now.

Zach Lee will start the opener on Thursday night for the Triple-A Dodgers, per broadcaster Alex Freedman, followed by Jharel Cotton, Jeremy Kehrt, Carlos Frias then Urias.

Though Urias is the only left-handed pitcher on the starting staff, OKC has a whopping five southpaw relievers, including three on the Dodgers' 40-man roster — Luis Avilan, Adam Liberatore and Ian Thomas.

Jose De Leon, who shot up prospect lists to national prominence after a strong 2015, will open the season one of a trio of pitchers to keep an eye on at extended spring training at Camelback Ranch in Arizona. The Dodgers want to monitor the innings of De Leon, 23, who jumped from 77 innings in 2014 to 114 in 2015.

"Jose De Leon is working diligently to become the strongest version of himself. Across the organization, there are few men more involved their own developmental process than Jose," said Dodgers director of player development Gabe Kapler. "We know we need to pay close attention to usage. More importantly, we see him as a part of our future in the major leagues, and we are taking steps with him to optimize for that outcome."

Another pitcher who will remain in Arizona to start the season is Yaisel Sierra, who turns 25 in June. The hard-throwing right-hander signed a six-year, $30 million contract with the Dodgers on Feb. 21, but didn't really begin his spring until March 1.

The third high-profile pitcher to remain in Arizona is Yadier Alvarez, the Cuban signed to a $16 million bonus in July. Alvarez is just 20 this year, so he wouldn't necessarily be in Triple-A, but before reaching an affiliate will remain in Arizona for a bit.

"Yadier is working on acclimating on and off the field, developing his secondary pitches and focusing on fastball command," Kapler explained. "[Pitching coordinator] Rick Knapp and our entire pitching staff are spending energy helping Yad be consistent with his delivery."

The Dodgers still plan on developing Sierra as a starting pitcher, though he might be able to help the big club out of the bullpen at some point this season.

"Sierra is uniquely professional at this stage in the game. He trusts our partnership with him and is devoted to staying in the moment," Kapler said. "We're not looking too far out ahead with him, but have plans to get him innings as a starter. That said, we expect all of our pitchers to be flexible and think of themselves as athletes, not starters or relievers."

Here is the 25-man active roster for Oklahoma City, which doesn't include catcher Vin DiFazio and infielder Josmar Cordero, both of whom who will start on the disabled list. Though not listed, non-roster outfielder Rico Noel is reportedly sidelined by an oblique strain, per J.P. Hoornstra of the LA Daily News.

OKC opens its scheduled on Thursday night in Nashville.