ARLINGTON -- The Dodgers’ biggest need as the Aug. 1 Trade Deadline approaches was abundantly clear before this weekend’s series against the Rangers in Texas. 

But in Sunday afternoon’s 8-4 loss to complete a second-half-opening nine-game road trip, that deficiency was magnified following two days of headline-grabbing fireworks at the plate.

If the Dodgers’ victories on Friday and Saturday -- a combined margin of 19 runs -- had them flying high thanks to a high-powered lineup, Sunday’s series finale brought them back to earth a bit. 

As a result, president of baseball operations Andrew Friedman will enter the final week before the Trade Deadline with a fresh reminder of what his No. 1 priority will be: starting pitching.

Sunday’s starter, rookie right-hander Emmet Sheehan, was staked to a 4-0 lead five batters into the contest when Max Muncy belted a grand slam off Texas starter Martín Pérez. It was Muncy’s fifth career grand slam and his franchise-record-tying third this season, as he became the sixth Dodger to hit three grand slams in one season and the first since Chris Taylor in 2017.

But Sheehan couldn’t capitalize. He gave up two runs in the first inning, three in the second, two more in the third and one in the fourth. Five of the eight runs that were scored against him over 3 2/3 innings were by players whom he walked, underscoring an issue that has become particularly concerning for the 23-year-old over the past several starts -- lack of command. 

“[Sheehan] overall wasn’t sharp,” manager Dave Roberts said. “I think that the stuff was down, the command of all his pitches wasn’t there. And you can’t defend a walk. So to put up a big number in the first inning and then come back and walk the first couple guys and put us in a tough spot -- it just wasn’t sharp today.” 

Roberts and Sheehan differed on their opinions about what led to the poor outing. Roberts thought the young right-hander was “tentative” and didn’t attack Rangers hitters, resulting in “a lot of non-competitive pitches.”

“When you get predictable and you don’t have overpowering stuff, it’s hard to get through a Major League lineup,” Roberts said. “ … He’s got to learn from it. … You’ve got to kind of let it rip. Major League hitters, they smell fear. They see blood and when there’s a weakness, they’re gonna go after you. … So it’s a reality check. I still believe the stuff plays when it’s thrown with conviction.” 

Sheehan’s velocity was, indeed, down across the board. His four-seam fastball, which had been averaging 95.7 mph on the season, averaged 94.6 mph on Sunday. His average slider velocity was down significantly, from 87.4 mph to 83.3 mph. 

For his part, Sheehan didn’t seem to feel conviction was the issue. 

“I think the only challenge is one that I gave myself, which is not being in the zone enough,” he said. “ … I don’t think I was tentative. I thought I was ripping my stuff.”

Regardless of what the reason behind the rough outing was, in the wider scheme of things for the Dodgers, it was a glaring reminder that this is a team with championship hopes despite currently being without three-fifths of its starting rotation. 

With Walker Buehler and Dustin May out for the season, and Clayton Kershaw still working his way back from left shoulder soreness, it’s been Julio Urías, Tony Gonsolin and three rookies -- Sheehan, Bobby Miller and Michael Grove -- who have been charged with seeing the Dodgers through this trying time for the pitching staff. 

In four starts since coming off the injured list, Urías has a 6.75 ERA, and in his last outing, he surrendered eight runs over five innings in Baltimore. Gonsolin hasn’t fared much better -- in six starts dating back to June 18, his ERA is 6.97. 

As for the rookies, they’re being asked to carry a heavy load, and as Roberts alluded to, they’re still learning on the job. 

It remains to be seen what the Dodgers do prior to the Trade Deadline, which is eight days away. But if winning the World Series -- something they did three years ago on the very same field as they played on this weekend -- is to remain a realistic goal, their starting rotation will need to improve. 

A star-studded lineup is undoubtedly a great asset. But it will only take you so far in October without the requisite starting pitching. An eventful series in Texas demonstrated those realities vividly for the Dodgers.