With the victory, Dallas Baptist has swept the two games between the squads this year, prevailing once in Dallas and on this night on the road.
Like Tuesday, the Sooners took the early 1-0 lead in the first inning when a pair of errors allowed center fielder Max White to come around and score after his double.
But the offense was largely stagnant from that point on.
"They are just not hitting right now," said OU head coach Sunny Golloway. "We have a lot of things not going right now. Hopefully things will start going right for us, that's baseball. Sometimes you are not as good as you look some days and not as bad as you look on others."
But they looked pretty bad in this one, recording just six hits and committing nearly as many errors, four.
DBU took advantage of a couple of those Sooner errors and plated three runs of their own in the top of the fourth, never looking back from there.
Sooner starter Dillon Overton, who didn't have his best outing, still struck out seven and walked just two but exited after the fifth inning, surrendering three runs, two earned in the losing decision.
Patriot second baseman Austin Elkins blasted a solo shot over the right field wall in the top of the seventh to extend the lead to three, but OU came back with one of its own on White's RBI single up the middle to make it 4-2.
However, the Patriots put it away in the ninth with four insurance runs thanks to the other two Sooner errors.
"You just have to wash it and come back and play new every day," Golloway said. "Our leaders have to be able to do that."
One leader who has been excelling as of late is White, who extended his hitting streak to five games.
The rest of the lineup, however, has really been struggling.
"The small things are getting better, we have to get better," White said.
They'll have their next opportunity when they take the road for a three-game set this weekend in Lawrence, Kan., against the Kansas Jayhawks.
"Our chance to get back in it and hopefully have a chance to go to the NCAA Tournament is winning Big 12 games, it's that simple," Golloway said. "We have to win Big 12 games."
First pitch is set for 6 p.m. Friday at Hoglund Park.