Weimer emerged as one of the Chicago Cubs' top starting pitchers in the first part of the 20th century. He went 21–9 with a 2.30 ERA in his 1903 rookie season and 20–14 with 1.91 in his sophomore year.
Weimer became a prominent figure among the Chicago Cubs' starting pitchers during the early 20th century. His impressive rookie season in 1903 showcased his skills, as he compiled a 21–9 record and a 2.30 ERA. He continued to excel in his sophomore year, posting a 20–14 mark and a 1.91 ERA.