ARLINGTON -- Jordan Lyles gave the Rangers their second straight short outing from a starter, and their bullpen couldn’t contain Padres rising superstar Fernando Tatis Jr.

Lyles’ outing should be more disconcerting, given how much the Rangers are counting on their rotation to be a strength this season. But Tatis had the Rangers fuming afterward by breaking one of the “unwritten” rules of baseball in the Padres’ 14-4 victory on Monday night at Globe Life Field.

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Lyles was tagged for seven runs (six earned) in four innings. Tatis drove in seven runs with a pair of home runs, but the Rangers had already let this one slip away before he was able to flex his muscles.

The Padres were leading, 10-3, when Tatis hit his grand slam off Rangers reliever Juan Nicasio. What made the Rangers mad was Tatis was swinging at a 3-0 pitch in the eighth inning of a seven-run game.

“I think there's a lot of unwritten rules that are constantly being challenged in today's game,” Rangers manager Chris Woodward said. “I didn't like it, personally. You're up by seven in the eighth inning; it's typically not a good time to swing 3-0. It's kind of the way we were all raised in the game. But, like I said, the norms are being challenged on a daily basis, so -- just because I don't like it doesn't mean it's not right. [But] I don't think we liked it as a group.”

Apparently not. Ian Gibaut took over for Nicasio, and his first pitch went behind Manny Machado, the next Padres hitter. Tatis, whose father played 11 years in the big leagues, seemed to understand after the game that it was not the right time to be swinging at a 3-0 pitch.

“I was locked in,” Tatis said. “I was locked in on the game. I was trying to produce for my team. That was on me. I was just trying to make a good pitch and put my barrel on it, and we got a result. I’ve been in this game since I was a kid. I know a lot of unwritten rules. I was kind of lost on this. Those experiences, you have to learn. Probably next time, I’ll take a pitch.”

The Rangers, with the two straight losses, are back under .500 at 10-11 and remain in third place in the American League West. Both losses were marked by short outings by their starting pitchers as Kolby Allard lasted just three innings in Sunday’s loss at Colorado. Lyles set down the side in order in the first inning before giving up five runs in the second.

“Overall, I need to do a better job preventing that crooked number,” Lyles said. “I made worse pitches in the first inning than I did the second inning. ... I've got to do better. I've got to stop putting our team in a bad spot.”

Lyles is now 1-2 with a 7.52 ERA after four starts and one relief appearance. In two games, the Rangers starters’ ERA has climbed from 3.40 to 4.20 on the season. Take out Lance Lynn, and the rest of the rotation -- not helped by the loss of Corey Kluber -- is 2-6 with a 5.57 ERA in 16 games.

Jimmy Herget followed Lyles and gave the Rangers two scoreless innings. That allowed them to threaten a comeback as a two-run double by Rougned Odor in the fourth and a run-scoring double by Joey Gallo in the seventh made it 7-3.

Then Tatis took over with a three-run home run off Jesse Chavez and then the grand slam in the eighth.

The seven runs allowed by the bullpen left Rangers relievers with a 5.63 ERA on the season. Take away the late-inning trio of Rafael Montero, Joely Rodríguez and Jonathan Hernández -- four earned runs over 23 innings -- and the rest of the relievers have a 7.32 ERA.

“We just got to make sure we’re getting our work in,” Woodward said. “We’re fearless out there. Keep grinding. Keep pushing. This is a weird year. We’ve been in this position a few games back. We have pretty good starting pitching coming up for us. We’re going to put our foot on the gas, try to get some runs early, and try to win some games.”