Beltre doubled and scored in the second inning, and then hit a two-run homer in the sixth to power AL West-leading Texas to a 4-2 victory over the Houston Astros on Tuesday night.
"This is what I'm supposed to be doing, right?" Beltre said. "I've been feeling better lately. Definitely."
"The only way I can really describe it, he's the MVP. He's having an MVP-caliber season," Ian Kinsler said. "He's one of the best players in the league on one of the best teams, and he does it night in and night out."
Beltre is hitting .434 (33 of 76) over his last 21 games, raising his season average 19 points to .326, third in the American League.
After a leadoff double in the second, Beltre went to third on a wild pitch and scored on an infield single by Alex Rios.
"He's been swinging the bat extremely well and been getting it done in situations when we really need him to get it done," manager Ron Washington said. "That's what Beltre is about, and it seems like every time we go down the stretch, he's right there ready to do it"
Matt Dominguez homered for Houston, which has lost seven in row and 13 of 14 against the Rangers.
Neal Cotts (5-2) struck out the first three batters he faced over 1 1/3 innings and was credited with the win. The lefty was the second reliever after Travis Blackley pitched four innings against his former team a week after being traded to Texas.
Joe Nathan struck out the side in the ninth for his 37th save in 39 chances.
Cosart allowed three runs over six innings, raising his ERA from 1.15 to 1.60. It was the first time in his seven major league starts that he yielded more than two runs.
"I thought command-wise, it was my best game," Cosart said. "I had command of two pitches, fastball and curve, and didn't have to use my changeup. They couldn't sit on one pitch."
Texas was down 2-1 when Kinsler drew a one-out walk in the sixth. Beltre then hit a drive to right for the first homer surrendered by Cosart in his 45 major league innings -- and one that had the 23-year-old biting his glove in disgust.
"That pitch was at his head. It wasn't even a strike," Cosart said. "I didn't think he would swing at it."
Blackley was brought up from Triple-A Round Rock to start in place of right-hander Alexi Ogando, who was put on the disabled list with right shoulder inflammation.
The 30-year-old Australian, who made 42 relief appearances for Houston, allowed three hits and two runs. The Rangers expected for him to throw around 65 pitches, and he threw 66, 42 for strikes.
"He did a good job," Washington said. "Other than (one pitch to Dominguez), he did what he needed to do, keep us in the game."
Chris Carter walked and scored on Dominguez's 17th homer in the second.
There were 11 pitches in the first, including a hard shot by L.J. Hoes that ricocheted off Blackley's foot toward the third base line. Jurickson Profar made a barehanded grab and threw in one motion to retire Hoes.
Astros manager Bo Porter quickly came out to unsuccessfully argue with umpire Lance Barksdale that Profar's throw pulled first baseman Mitch Moreland off the bag. Under the expansion of video review planned for next season, it was the kind of challenge Porter may have won.
Max Stassi, called up from Double-A Corpus Christi earlier Tuesday, made his major league debut as the designated hitter and got a single in the fifth. He also will remember what happened after the first of his two hits.
A comebacker by Marwin Gonzalez was snagged by reliever Jason Frasor, who turned and made a high throw that went off shortstop Andrus' glove and caught by second baseman Kinsler backing up the play. But Stassi, apparently thinking he was already out, wandered off second base and was tagged by Kinsler.
"He told me, 'Bo, this never happened to me in no league, and it's not going to happen again,' " Porter said. "I told him if you are a forceout, you don't leave the base until the umpire says you're out."
Stassi, a catcher, was called up after C Carlos Corporan was put on the seven-day concussion DL after being hit in the mask by a foul tip Monday night. Corporan was returning to Houston to see a specialist.