Rangers general manager Jon Daniels and manager Ron Washington were reminded once again Friday that what happened with their starting rotation in 2011 may never happen again.

Five pitchers, 155 starts out of 162 games.

It didn't happen last year when the Rangers used 11 starters. It's not going to happen this season after the club announced before Friday's game against Seattle that Opening Day starter Matt Harrison is out until at best around the All-Star break.

For the here and now it means two-fifths of the Rangers' rotation will be comprised of rookies -- 24-year-old Nick Tepesch and 24-year-old Justin Grimm. In other words, the Rangers are wandering into a big unknown. Tepesch looked great in his first start and Grimm has a lot of potential, but losing Harrison is a major blow.

"That was the one thing I felt like we were vulnerable to was an injury to one of the main guys in our rotation," designated hitter Lance Berkman said. "We have four excellent starting pitchers, but we have a thin list of candidates to replace (them). They have the ability to do so, but it's a track record issue. Every year there's some adversity to fight through and this might be it."

Berkman's a veteran player being honest. It's no knock on Grimm or Tepesch. Harrison won 34 games in 2011 and '12. Grimm will make his fourth career start Sunday, one more than Tepesch has made.

Daniels said Friday he doesn't expect to run out and make a trade. April doesn't make for the best trading season and the Rangers do have guys rehabbing in Arizona that could make an impact -- Colby Lewis, Neftali Feliz and Martin Perez.

"We're always keeping our eyes open," Daniels said. "But I don't think we'll do anything from outside. We'll play it out. We like the guys we've got. We like the guys that are on the mend. That's obviously an important group for us in Arizona."

The replacements, as we'll call Lewis and Co., won't be available until late May or June. So it's up to Grimm for now. His first task is to better the four innings in his start last week in Seattle.

"Justin had one start, wasn't at his best and I thought he battled through it without his best command," Daniels said. "He'll go again Sunday and we'll go from there."