"No one outing is going to define me, whether it's good or bad," said Archer, who moved to 9-6 after taking the loss. "Constantly trying to get better. Constantly working towards my potential. Clearly not there yet."
The Rays' offense gave Archer leads of 1-0 and 3-2, but each time the Royals came back.
Lorenzo Cain erased the 1-0 lead with a two-run homer to center field in the third.
"That was just a hanging slider," Archer said. "It wasn't a good pitch. He's a three-hole hitter for one of the best teams in baseball. That's what they usually do."
The 3-2 lead evaporated in the fifth when the Royals scored five times in the fifth via RBI singles by Cain, Eric Hosmer and Salvador Perez, along with a two-run double by Kendrys Morales.
The Royals finished their assault on Archer in the sixth when Jarrod Dyson hit a two-run, inside-the-park homer.
"They did find some holes, but they also hit some balls hard," Archer said. "Obviously, I hold myself to a higher standard. I want to give the team a better performance. I did my best, man.
"Again, we didn't win the game, but the way we surged and fought the entire game kind of just shows who we are. Even through a rough patch, we still can do it, and do it against one of the better teams in baseball."
Archer, who was named to the American League All-Star team on Monday, was asked if he was disappointed by his outing given his new status.
"Just disappointing in the fact that I didn't give my team hardly a chance to win," Archer said. "We put up seven runs and usually when we can do that we win.
"... I really was hoping to walk away with a split series here and go home and be in a good position at the break. And we still can be. [Being named to the All-Star team] wasn't even on my mind at all."
Rays manager Kevin Cash allowed that Wednesday night's outing by Archer "was a little unusual" given the way Archer has pitched all season.
"But even the good ones have some tough nights," Cash said.