He had no choice because the numbers told the story.
The Cowboys' starting unit had three offensive possessions and zero scores. The drives featured one first down, a sack and two three-and-outs.
"Not real good," Garrett said. "We didn't play with great rhythm."
Of the 11 offensive snaps from the first-team offense, there were two good plays. Wide receiver Dez Bryant made a nice leaping catch for a 24-yard gain, and Tony Romo hit tight end Jason Witten for eight yards.
Yup, that's it.
Unless you want to count Romo's escaping a sack to complete a pass to Witten for a 2-yard loss as a good play.
"We wanted more," Romo said. "We made some mistakes, and it cost us. There will be some good stuff to evaluate and get better. We have to get better from [Monday's] game, and we will."
It's easy to be critical of a Cowboys offense that scored the fewest points in a preseason victory in franchise history.
Then again, this offense was playing with a guard, David Arkin, at center, a position he's never played before. Last year's No. 4 receiver, Kevin Ogletree, was starting alongside Bryant. Derrick Dockery and Mackenzy Bernadeau started at guard, but they still need more time together to develop. And rookie James Hanna was seeing snaps as the second tight end.
"We did play some different combinations of guys, we get that," Garrett said. "We're expecting these guys to come in, we have a next-man-up philosophy, so this was their chance to go in there and play. Each of those guys, at first glance, did some good things and some things we got to get better at. Overall, it was not a good enough performance. But it's still early on in camp, but we just got to learn from it."
Garrett praised Arkin for not fumbling the ball on snaps, but he also pointed out that the center allowed Romo to get sacked when he failed to pick up Tommy Kelly on a screen play. Garrett added that Ogletree, who finished with one catch, did some good things and that he was pleased with Dockery and Bernadeau.
The Cowboys finished with the seventh-best passing offense in the NFL last season, but Romo's offense came up empty Monday night.
"When you look at the coverage on some of the plays, I think we could have got to some things that we really like versus what they were doing," Romo said. "But that's not what we do in preseason, and for good reason."
The run game was bad.
Holes were not there.
It's never a good thing when a converted fullback, asked to participate at running back due to injuries, leads the team in rushing, as Jamize Olawale did with 42 yards on 12 carries.
At least the Raiders had a legit running back, former Cowboy Lonyae Miller, lead them in rushing. Miller finished with 15 carries for 39 yards. Starter Darren McFadden had 20 yards on two carries, including one for 16 yards.
"It took us a couple of drives to make some first downs," Garrett said. "Dez made a good play, a completion to Wit was good, but for the most part we didn't run it as well as we needed to and didn't drive it as well as we needed to. I think the self-inflicted wounds were a part of that. But we have to learn from it and go back and watch each individual play, technique assignments and how 11 guys did and understand that everybody has to do their job for us to be a good offense."
It's very early in the preseason.
Wide receiver Miles Austin didn't play. Center Phil Costa was out. Offensive guard Nate Livings was out. Bernadeau will develop chemistry with the offensive line, and at some point the interior of the line will improve.
But if we don't see signs of progress in the preseason, the Cowboys will have some problems.