WASHINGTON -- Right-hander Jhoulys Chacin will throw a two-part bullpen session on Thursday, when the Rockies have an optional workout at Coors Field, as part of his comeback from a nerve damage issue in the right side of his chest.

Chacin, who was expected to be a staff leader but was 0-3 with a 7.30 ERA in five starts before going to the disabled list, has been gradually regaining arm strength.

The bullpen session will be interrupted in the middle with a rest period to simulate what happens between innings.

"All indications, from what I hear, is that he's coming, his arm strength is coming back, the ball is coming out of his hand better than it had been," Rockies manager Jim Tracy said.

Tracy also said catcher Ramon Hernandez caught seven innings for Triple-A Colorado Springs on Friday as part of his rehab assignment for a left hand strain. Tracy said he has not determined the playing time between Hernandez, the Opening Day starter, and rookie Wilin Rosario, who has made dramatic strides in Hernandez's absence, but he will be careful not to overuse Hernandez and possibly create another injury.

Old approach part of Colvin's new success

WASHINGTON -- The Rockies' Tyler Colvin is on a roll of any player's dreams.

His .897 slugging percentage from June 9 through his two-homer performance against Nationals All-Star Stephen Strasburg on Friday night led the Majors by a large margin. Going into Saturday afternoon against the Nationals, he had driven in 10 of the Rockies' 15 runs on their current road trip.

A rigid kind of fellow would be worrying about how the All-Star break will disturb his roll. But not Colvin.

"I'm going back to South Carolina with my fishing buddy in North Augusta," Colvin said. "I'm going fishing for bass, big bass, and I'm pretty good."

He showed a picture of a bass that was every bit of eight pounds. But Colvin added his fishing was for sport. That fish was happily released back into the water. Pitchers only wish he could be so kind to them.

As a rookie with the Cubs in 2010, Colvin hit 20 home runs. But last year, as Colvin attempted to increase his power numbers, the pitchers had him hook, line and sinker, to the tune of a .150 batting average. New Cubs management traded him and infielder JD LeMahie (now at Triple-A Colorado Springs) to the Rockies for third baseman Ian Stewart and pitcher Casey Weathers. Colvin and Stewart were considered the keys. Both were coming off bad years and -- wisdom went -- needed changes of scenery.

It has worked for Colvin. He entered Saturday's start against the Nationals batting .311 with 13 home runs and 40 RBIs -- strong numbers, considering that it wasn't until this month that his playing time -- at three outfield positions plus first base -- became regular. While Stewart struggled early and will miss the rest of the year because of wrist surgery, the Rockies find themselves with a player who can be a big part of the future.

Colvin has been used to spell Dexter Fowler in center, and on rare occasions, All-Star Carlos Gonzalez in left. With veteran first baseman Todd Helton battling hip issues and a prolonged slump, manager Jim Tracy has been using Colvin at first base or in right field when Michael Cuddyer plays first base.

It all happened because Colvin reached into his own past for the right hitting approach.

Coming off 2010, Colvin felt he could increase his power. Working with then-Cubs batting coach Rudy Jaramillo, he carried his hands higher in his stance, under the theory that grater separation would mean more power.

The thought process that came from the need to hit home runs ruined a good hitter. Colvin made notes about opposing pitchers in a spiral notebook, a practice that continues. At his best or at his worst, he loves talking about hitting, and he had many discussions to find out why he was struggling. He figured it was a problem only he could solve.

"When you're going bad, you search," Colvin said. "But usually, you're searching for nothing. It's all up here [in the mind]. You go up and have a good approach and that takes care of everything.

"The approach just wasn't there. I was thinking and talking to other hitters, and figured out I wasn't going up there looking for anything. I was just going up there swinging. It was the mindset that I was going to just hit a home run.

The Rockies compared video of 2010 and '11 and told Colvin in early phone conversations they wanted the 2010 version. Manager Jim Tracy brought him to Denver for hitting sessions. Hitting coach Carney Lansford lives in Arizona and was also able to work with Colvin at the Rockies' Scottsdale complex.

Lansford was already familiar with Colvin, who had played in the Cubs' organization with Lansford's oldest son.

"I got to watch him when he was in short-season, and that's the kind of hitter he was," Lansford said. "I just said, 'I just want to get you back to the kind of hitter that I remember you being.' He was more than thrilled to hear what our approach was. Just let him be the hitter he's capable of being."

Colvin entered Saturday with a less-than ideal .339 on-base percentage. But from the beginning of his hot streak on June 9 through Friday, his on-base was .410. His ability to spoil good pitches from Strasburg on Friday before his second homer, a two-run shot on the eighth pitch to the at-bat, could be an indication that there's more to him than a hot streak.

If Colvin can fight off good pitches, lay off chase pitches and destroy mistakes, it could be open season on pitchers in the second half.

Post-break rotation revolves around Pomeranz

WASHINGTON -- The Rockies' pitching plan coming out of the All-Star break will give rookie left-hander Drew Pomeranz, who has not given up an earned run in 12 1/3 innings in two starts after his return from Triple-A Colorado Springs, and veteran lefty Jeff Francis an extra day's rest on the first turn.

The key to the rotation strategy is Pomeranz (1-3, 3.06 ERA). Rockies are operating on a four-starter system, but Pomeranz had been throwing in a five-man rotation at Triple-A Colorado Springs and has yet to throw with one fewer day of rest. His first turn on three days' rest will be July 24.

Rookie left-hander Christian Friedrich (4-6, 5.98) will throw the first game out of the break, next Friday against the Phillies. Jeremy Guthrie (3-8, 6.28 going into Sunday's final game before the break, against the Nationals) and Pomeranz will throw the final two games of that series.

Following that set is a three-game series with the Pirates. Starters will be Francis (2-1, 5.16 going into Saturday against the Nationals), Friedrich and Guthrie. The Rockies are not scheduled to play on July 19, which means Pomeranz and Francis will get the extra day.

Entering the season, the Rockies were looking for ways to monitor the workload of Pomeranz, who is in just his second year of professional baseball. The Indians selected him in the first round of the 2010 MLB First-Year Player Draft, but he didn't pitch until Spring Training 2011.

Pomeranz finished the year in the Majors with the Rockies, who acquired him as part of the Ubaldo Jimenez trade, but he didn't have a full year of pitching.

Pomeranz didn't sign his first pro contract until August 17, 2010, so Major League rules didn't allow him to be officially traded until a year past that point. The trade took place on July 31, 2011, but Pomeranz had to wait until his anniversary date to pitch. After his first game at Double-A Tulsa, Pomeranz underwent an emergency appendectomy. After recovering, he pitched one more game for Tulsa, then made his Major League debut on Sept. 11.

In all, Pomeranz entered 2012 with 119 1/3 pro innings. He is at 82 innings at the break this season, including 31 1/3 in the Majors.