"He's a first baseman ... natural," Washington said. "That's all that matters. It's not what he can do offensively. All that matters is he can move around that bag and do what needs to be done."
Berkman has played 762 games at first base, but has been limited to designated hitter duty this season after coming off two operations on his right knee last year. Thursday was only his second start of the season at first base, although he had no trouble when he played there on May 27 against Arizona. The question is how the knee will hold up playing regularly in the field.
"I think it's a day at a time at this point," Berkman said. "I can't predict how I'll feel tomorrow or the next day. We'll just see how it goes."
McGuiness has been playing first base at Round Rock and was hitting .275 with six home runs and 34 RBIs over 55 games. He has a .382 on-base percentage and a .477 slugging percentage, and is hitting .317 in his last 35 games.
The Rangers did not consider Mike Olt, who has played just five games since coming off the disabled list. He missed a month because of blurred vision. Olt is 8-for-21 with two home runs since his return but also has nine strikeouts.
"He's recovered from the vision issue and is doing well," general manager Jon Daniels said. "He needs more at-bats to catch up, but reports are he hasn't missed a beat."
Moreland injured himself running the bases in the seventh inning of the Rangers' 3-2 victory over the Red Sox on Thursday. He returned to Texas and had an MRI, which showed a Grade 1 strain. Moreland was on the disabled list from June 20 to July 29 last season with a strained left hamstring. He was hitting .288 with 12 home runs and 29 RBI in 58 games this season.
"The report is Mitch will be out at least two weeks," Daniels said. "Hopefully it will be close to that. Chris is a good defender at first, he gives you a good at-bat and has earned the opportunity."
McGuiness was one of three players acquired from the Red Sox on July 31, 2010, for catcher Jarrod Saltalamacchia along with pitcher Roman Mendez and catcher Michael Thomas. The Indians took him this winter in the Rule 5 Draft, but returned him to the Rangers at the end of Spring Training.
He was named the Arizona Fall League Most Valuable Player last year, batting .283 with four home runs and 27 RBIs in 25 games for Surprise. He also came close to making the Indians' Opening Day roster.
When the Indians returned McGuiness to the Rangers, Cleveland manager Terry Francona said, "I've said it before, I wish he wasn't a Rule 5. It's hard for a position player to skip Triple-A and come to the big leagues. It's not altogether fair to expect them to be able to put up numbers. There's so much to like about him."
To make room for McGuiness on the 40-man roster, Texas placed pitcher Colby Lewis on the 60-day disabled list. Lewis has already served more than 60 days on the disabled list while recovering from flexor tendon surgery, so the move doesn't impact his status.
• Pitcher Joakim Soria, who had Tommy John elbow reconstruction surgery 14 months ago, threw 30 pitches in a bullpen session on Wednesday in Surprise, Ariz., and has a 35-pitch session scheduled for Saturday. If that goes well, he could resume throwing live batting practice next week in either Surprise or Arlington. The Rangers hoped to have him in the bullpen by now, but his return was delayed by a strained muscle in the front of his right shoulder.
• Berkman went into Thursday's game just 5-for-31 with one RBI in his last nine games and said, "I'm just not getting any hits. It's just a bad stretch."
• The Rangers have signed pitcher Omarlin Lopez, 19, to a $825,000 signing bonus and assigned him to the Dominican Summer League. He is a converted shortstop from the Dominican Republic.