ARLINGTON -- The Rangers' farm system has taken some big hits in the past few years because of Major League trades. But player development director Jayce Tingler said he's still encouraged by what remains.
"I think we have some undervalued guys," Tingler said. "We have a nice group in the upper levels that could contribute to a championship club and some impact guys at the lower levels."
Thursday was Opening Night in the Minors. Here are some players to watch in the Rangers' system.
Round Rock (Triple-A)

Here's the pitch:Nick Martinez and Dillon Gee are leading candidates to be the Rangers' fifth starter when needed. But the Rangers really want to look at right-handers Tyler Wagner and Carl Webster, former top prospects acquired in the offseason.

Big prospects: First baseman Ronald Guzman is a Nomar Mazara-class hitting prospect and outfielder Preston Beck has impressive exit velocity off the bat.
Keep an eye on: Right-hander R.J. Alvarez is a power reliever who could help in the big leagues.
On the spot:Keone Kela.
Frisco (Double-A)

Here's the pitch: The crown jewels of starting pitching prospects are here with Yohander Mendez, Connor Sadzeck and Ariel Jurado.

Big prospects: Club is strong up the middle with catcher Jose Trevino, shortstop Michael DeLeon and second baseman Andy Ibanez.
Keep an eye on: An interesting outfield led by Scott Heineman, Luke Tendler and Jose Cardona.
On the spot: Right-hander Colin Wiles was the 53rd overall pick in the 2012 Draft, but he has yet to pitch above Class A.
Down East (Class A Advanced)

Here's the pitch: Impressive group of starters led by left-handers Brett Martin, Joe Palumbo and Wes Benjamin, and right-hander Pedro Payano.

Big prospects: Josh Morgan was drafted as an infielder, but he is transitioning to catcher.
Keep an eye on: Infielder Luis La O was signed out of Cuba where he played six seasons in the National Series and hit .329.
On the spot: Outfielder Jario Beras had a big finish at High Desert last year, hitting .321 with 12 home runs and 38 RBIs in his last 37 games.
Hickory (Class A)

Here's the pitch: Right-hander Jonathan Hernandez could be poised for a big year as he adds strength, durability and velocity.
Big prospects: This will be outfielder Leody Taveras' first full season in the Minor Leagues. He is 18, but already is ranked as the Rangers' No. 1 prospect by MLBPipeline.com.

Keep an eye on: The Crawdads have three prized infielders in Anderson Tejeda, Yeyson Yrizarri and Ti'Quan Forbes.
On the spot: Jake Lemoine was a fourth-round pick in the 2015 Draft. He has first-round talent, but Lemoine has been battling shoulder issues. He will pitch as a reliever.