Philadelphia Phillies Klassen was selected by the
Philadelphia Phillies in the sixth round of the
2023 Major League Baseball draft. He made his professional debut in 2024 with the
Single-A Clearwater Threshers. Over the first 2 months of the season, he posted a 0.71 ERA, 0.87 WHIP and 57 strikeouts across 38.0 innings pitched. On June 11, Klassen was promoted to the
High-A Jersey Shore Blue Claws. At High-A, he made 5 starts, posting a 4.22 ERA with 1.17 WHIP and 32 strikeouts in 21.1 innings pitched.
Los Angeles Angels On July 27, 2024, the Phillies traded Klassen and
Samuel Aldegheri to the
Los Angeles Angels in exchange for
Carlos Estévez. In 2024, he played in four teams, posting a 3.10 ERA with 135 strikeouts and 46 walks in 93 innings pitched. Klassen started 2025 with
Double-A Rocket City Trash Pandas. He was named the Angels’ representative in the 2025
All-Star Futures Game on July 12. He was promoted to the
Triple-A Salt Lake Bees on September 16. Between the two levels, he had a combined ERA of 5.22 with a 4-12 record, 134 strikeouts and 47 walks in 108.2 innings pitched over 25 starts. On April 5, 2026, the Angels promoted Klassen to the major leagues, and he pitched innings later that night in a debut against the
Seattle Mariners. After pitching another two innings on April 11, Klassen bruised his right index finger and his ERA stood at 13.50, resulting in his return to Salt Lake. ==References==