SURPRISE, Ariz. -- Rangers pitcher Yu Darvish will remember St. Patrick's Day for more than the usual celebration of Irish culture.
St. Patrick's Day was the day Darvish underwent Tommy John surgery last year. He celebrated the one-year anniversary by throwing another bullpen session Thursday morning. Darvish threw 25 pitches, including a mixture of sliders and curves.
The target date for Darvish's return remains mid-May to early June.
"From watching Yu throw today, I think he has progressed at the rate we felt a guy the caliber of Yu Darvish would progress," Rangers manager Jeff Banister said. "He has had no significant setbacks. As I watched him throw, the one thing I was impressed with is his feel for the baseball and spinning the baseball. This is a guy who spins the baseball as well as anybody."
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Darvish, talking with Banister after the session, expressed displeasure at his inconsistent command.
"That's also going to be a process," Banister said. "I'm sure a competitive guy like him, throwing in the bullpen, he'll get to the point where he wants to see hitters. He's got to stay patient until the time is necessary."
The Rangers aren't sure when that will be. At some point, Darvish will start increasing his pitch count, then he will throw batting practice and simulated games, then go on a 30-day rehabilitation assignment. That will like consist of six starts in the Minor Leagues.
"He is still on the medical side," Banister said. "He is still not turned over to our side completely. We work with the medical side, but the throwing program is still under their watchful eye."
Darvish is on a 14-month rehab progress, a rather recent development. Up until a few years ago, pitchers returning from Tommy John were expected to miss 12 months. Also built into that plan was the assumption that a pitcher wouldn't be all the way back until the second season after his return.
The 14-month plan -- which goes from date of surgery to return to big leagues -- offers more hope there will be no setbacks in the process and the pitcher will be as close to full strength as possible upon his return.
"Full strength includes all factors," Banister said. "Delivery, consistency, command, being able to respond between starts, no missed starts. … When we talk about full strength, we take all of that into account. Strength-wise and overall velocity, they are usually pretty close."
Marlins pitcher Jose Fernandez went nearly 14 months between starts. His last start before the surgery was May 9, 2014. Fernandez returned on July 2 of last season and was 6-1 with a 2.92 ERA and 10.99 strikeouts per nine innings down the stretch. His fastball averaged 95.1 mph in 2014 and 95.8 last season after his return.
Rangers pitcher Martin Perez, who had Tommy John surgery on May 19, 2014, was also on the 14-month plan. His first start in 2015 was on July 17 and he was 3-6 with a 4.46 ERA in 14 starts. Perez's velocity went from 90.2 in 2014 to 91.8 last season.
The Rangers are confident about how Darvish will pitch when he returns at some point in May or June.
"Yes. How he has gone about his rehab, what he was previously, the dedication in getting himself back and what our eyes tell us when he is throwing," Banister said. "This guy is well beyond the bell curve of talent. I've got to believe at full strength, when he is ready to go, he'll be a pretty good pitcher."
Worth noting
• Shin-Soo Choo is dealing with mild back stiffness and is day to day.
• Elvis Andrus and Josh Hamilton were excused from Thursday's workout because of illness.
• Rangers advance scout Adam Lewkowicz underwent surgery to repair a herniated disk in his back in Dallas. In his eighth year with Texas, Lewkowicz scouts the upcoming opponent as well as evaluating the Rangers' on-field performance. He is also a liaison between the coaching staff and front-office analytics.