It was the first time in 32 years that the Rangers took a shutout into the eighth and then gave up seven runs in an inning.
"The bullpen has been strong all year," Lewis said. "It was a rare game for them. It's just one loss."
Lewis was trying to give the Rangers' starters their first win since Yovani Gallardo beat the Mariners on April 17 in Seattle. They were 0-6 with a 4.26 ERA in their previous 10 games before Lewis took the mound.
Lewis allowed only two hits and two walks, and did not allow a runner past first base. He struck out eight before leaving after throwing 97 pitches over six innings. But Lewis also chastised himself for walking two batters with two outs in an inning.
"Otherwise I could have pitched into the seventh," Lewis said.
The offense gave him early run support. Kyle Blanks and Prince Fielder had solo home runs that gave the Rangers a 2-0 lead. The Rangers had hit just one home run in their previous six games.
Shin-Soo Choo had a double in the fourth inning that snapped an 0-for-21 slump. Adrian Beltre had a run-scoring single in the seventh, his first RBI of the season aside from two solo home runs.
The five runs were the most the Rangers scored in nine innings since a 7-1 victory over the D-backs on April 21. But the Rangers were not able to come away with the victory.
"It's a tough loss, no doubt about it," Rangers manager Jeff Banister said.