Despite two solo homers by Ryan Blake and one by Adam Greenberg, UNC (5-5) lost to the Golden Bears 7-4 at Boshamer Stadium.
"We're not going to win games hitting solo home runs like we did today," Fox said. "We've got to hit-and-run, we've got to steal bases and then hit a double. We're not an all-or-nothing team, and we can't fool ourselves into thinking that."
The contest was the last of a three-game series between the two schools this weekend. In Friday's doubleheader, the Tar Heels lost the opener 4-2 but rebounded to win the second game 7-5.
In both losses, UNC led until the final three innings.
The Tar Heels' offensive firepower seemed evident in Sunday's contest with Greenberg's leadoff homer over the left field wall. Three batters later, Sean Farrell singled to bring in Chad Prosser for a 2-0 lead.
But UNC starting pitcher Garry Bakker got into trouble in the fourth inning despite a two-out, 0-2 count against John Baker. Baker drew a walk, and the Golden Bears took advantage to get a spurt of runs.
Brian Horwitz followed the walk with a single to left, and in another two-strike situation, Jeff Dragicevich laced the ball down the third base line to score Horwitz and Baker, making it a 2-2 contest.
"You get a two-out walk, and it kills you every time," Fox said. "And that's a team that just took advantage of a walk, and you have to give them credit. If you don't get it in the right spot, with aluminum bats, it will get put in play."
Blake's first homer temporarily gave the Tar Heels a 3-2 lead in the fourth, and then 4-2 on his second shot in the fifth.