Cole needed 43 pitches to get out of a five-run first inning, when he struck out Gallo with the bases loaded. Cole's ERA went up from 3.24 to 5.22 after he was charged with all of the runs as the Rangers won 9-4 on Saturday night.
"I'm not trying to throw a pity party. It was a bad start. It's probably the worst of my career," said Cole (1-3), who last season didn't take his third loss until his 22nd start, when he was 10-3 on July 30.
It wasn't until Gallo took a called third strike on Cole's 32nd pitch that the right-hander finally recorded an out.
Gallo pulled a ball deep for the second night in a row, this time curling a homer over the top of the right field pole in the third inning to make it 6-0. His eighth homer of the season, measured at 433 feet after coming off the bat at 111 mph, followed a 442-foot drive down that line in the series opener.
"We're all kind of in awe," Rangers manager Chris Woodward said. "Every time the ball comes off his bat, you just think you're going to see something you've never seen before."
Asdrubal Cabrera accounted for five runs, driving in three and scoring twice.
That was after a series-ending 4-0 loss to the Rangers when Cole was clearly agitated when he immediately went to the plate umpire after recording his final out in the sixth. He was upset about being limited on his warmup pitches, and maybe a call or two. Manager AJ Hinch and hitting coach Alex Cintron were ejected early in that game for arguing balls and strikes when Houston was batting.
Cole's second start this year against the Rangers went sour quick. While he struck out nine in his 4 1/3 innings, the nine runs, and eight earned, he allowed were both career highs.
Shin-Soo Choo had a leadoff double, reaching safely in his 14th start in a row. Danny Santana followed with an RBI single, the first of his three hits. Gallo's strikeout came after consecutive walks, including Elvis Andrus on a 10-pitch at-bat that ended with a 99 mph fastball that appeared to be over the plate.
"Every time we face quality pitching like yesterday (Justin) Verlander and today Cole, you have to fight, man. It won't be an easy at-bat," Andrus said. "We had a great plan against him today, and everybody sticks to that plan."
Cabrera then blooped a two-run single to shallow left between two fielders before a two-out error led to another run.
"We had a difficult first inning. It started there, about anything that could happen badly in that inning happened," Hinch said. "Everything spiraled a little bit."
Cole felt he might have tipped some of his pitches, but credited the Rangers for how they executed against him.
"He got a little fast early, it just looked like he was trying to grunt his way through his outing and just get to the next pitch" Hinch said. "He reached deep into his tank of 98, 99 (mph) early. When he's doing that, he's trying to get out of that big inning. All in all just a bad night."
AND THE WINNER IS
Shawn Kelly (3-0) worked 1 2/3 scoreless innings in relief of starter Adrian Sampson, who allowed hits to the first four batters in the fifth.
Rangers: 2B Rougned Odor (right knee sprain) took some groundballs and hit in the cage. Manager Chris Woodward said Odor "let loose a little bit" after previously being a bit tentative moving side to side. Odor is still one to two weeks away from getting back in the lineup.
Astros: RHP Collin McHugh (3-1, 1.96), who threw 9 2/3 scoreless innings in six relief appearances against Texas last season, starts the series finale.
Rangers: RHP Shelby Miller (0-1, 9.00) has thrown only 10 innings in his three starts, and averaged 24.2 pitches per inning.
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