PHOENIX -- Team USA manager Mark DeRosa admitted he's managing the needs of his pitchers and their parent clubs as much as he is each game -- all of which may have contributed to a stunning 11-5 loss to Mexico in Round 1 of the WBC on Sunday night.

It was the second-worst loss by a U.S team in WBC history.

A poorly pitched game by the U.S. was compounded by the fact that DeRosa didn't feel comfortable making moves solely for the sake of winning.

"It's tough," he said afterward. "You're trying to massage innings. You're trying to protect these guys. You're trying to honor their parent clubs."

DeRosa made several moves which were impacted by the needs of his pitchers. One of them led to leaving reliever Brady Singer in the game during a key moment in the fourth inning, when Mexico's first baseman, Joey Meneses, hit his second home run of the night. The three-run shot put Mexico up, 7-1. That came after Kendall Graveman threw only five pitches in the third inning to get out of a jam.

"A lot of these guys are restricted from cleaning up a dirty inning and going back out," DeRosa said.

He gave the same answer about pulling Devin Williams after just one pitch in the eighth. Of course, every manager in the tournament is under the same restrictions.

"There's a lot of honoring parent clubs' wishes to get these guys ready for the regular season," DeRosa reiterated. "You're kind of limited in the number of arms you have down there. You have to push some guys."

Singer, and later Daniel Bard, were forced to stay in the game even though they were struggling. Mexico continued to add on runs, pulling away for the easy victory.

But it wasn't just poor pitching that did the U.S. in on Sunday. Mexico outplayed the U.S. in every facet, pleasing most of the 47,534 in attendance at Chase Field.

Meneses set the raucous crowd off with home runs in the first and fourth inning while Team USA played shaky defense and produced very little on the base paths until the game was out of reach.

"We're a really good baseball team," Singer said after giving up four runs on four hits. "I'm not too worried about it. We have to come back fighting tomorrow."

Both the U.S. and Mexico are 1-1 in pool play with two games remaining as the top two teams in the five team pool advance. "It's win or go home," catcher Will Smith said. "That's how we're treating it."

They're going to need a better all-around effort. Their win against Great Britain on Saturday wasn't overly impressive. They take on Canada on Monday; they beat Great Britain 18-8 by mercy rule.

"The vibe is still the same," shortstop Tim Anderson said. "You look around and see who's in the locker room and there's nothing to complain about. We have a bunch of dudes in there. It's just a matter of time before things start clicking."

Mexico has won three straight against the U.S. in WBC play.