Taiwanese starter Kai-Wei Teng moved closer to the team strikeout record, but the Flying Squirrels fell 7-3 in the final game of a six-game set to the Harrisburg Senators at The Diamond on Sunday.
Teng (5-12) took the loss, allowing five runs over 5 1/3 innings. He struck out nine batters, bringing his season total to 153.
The single-season franchise record is 165, set by Eric Surkamp in 2011.
Armani Smith walked three times for Richmond, which dropped four of six in the series.
Top prospect Robert Hassell III hit his first home run for Harrisburg since Washington acquired him from San Diego in the Juan Soto trade.
Wilson Garcia also homered for the Senators.
The Flying Squirrels next travel for a series against the Bowie Baysox in Maryland. The first game is slated for Tuesday at 6:35 p.m.