Former Royals pitcher from Lucas Erceg trade already on the move again

At the 2024 trade deadline, the Kansas City Royals made a major move to solidify their relief corps for the run to the postseason by acquiring closer Lucas Erceg in a trade with the Athletics. In return, they sent pitcher Will Klein — who had made his MLB debut with the Royals just three months prior — to the A's, alongside minor leaguers Mason Barnett and Jared Dickey.

Now, Klein is already on the move to his third team is less than six months, with the A's trading the 25-year-old to the Seattle Mariners on January 21 in exchange for international bonus pool space.

Athletics trade former Royals pitcher Will Klein to Seattle Mariners

Coming out of Eastern Illinois University, Klein was selected by the Royals in the fifth round of the 2020 MLB Draft with the 135th overall pick, and he made his professional debut with the team's High-A affiliate in 2021. After posting a 3.20 ERA with a 1.24 WHIP and 121 strikeouts in 70.1 innings out of the bullpen that season, MLB Pipeline named Klein the Royals' Pitching Prospect of the Year, and he was promoted to the Double-A Northwest Arkansas Naturals the following year.

The right-hander missed the start of 2022 due to shin splints, and when he returned from the IL in May, he was trialled in the starting rotation before being moved back to the bullpen. Even as a reliever, Klein struggled through his second season in the minors, finishing 2022 with an alarming 10.51 ERA and 2.43 WHIP in 43.2 innings of work (30 games, 3 starts).

Klein stayed in Double-A to start 2023, but after appearing to return to form — 3.38 ERA in 29.1 innings — he was promoted to the Triple-A Omaha Storm Chasers in June. In 35 innings in Triple-A, he posted a 5.66 ERA with a 1.86 WHIP and 49 strikeouts, and was chosen to represent the Royals at the 2023 All-Star Futures Game. To protect him from the Rule 5 Draft, the Royals added Klein to their 40-man roster on November 14, 2023, but he was optioned back to Triple-A to start the 2024 season.

On April 25, 2024, Klein was called up to the majors after pitcher Alec Marsh landed on the 15-day injured list with a right elbow contusion, and he made his MLB debut that same day. Klein made five appearances out of the bullpen for the Royals before he was traded at the end of July, posting a 6.35 ERA with a 2.00 WHIP and 6 strikeouts in 5.2 innings. He only made 3 appearances for the Athletics before the end of the 2024 season, allowing 5 earned runs in just 1.2 innings on the mound.

Despite his struggles, Klein is brimming with potential as a fierce back-end reliever. His arsenal includes a four-seamer that reaches 97 mph, as well as two breaking balls — a curveball and a slider — and at just 25 years old, his questionable first few appearances in the majors shouldn't be enough to even consider writing him off.

It's not yet clear whether Seattle plans for Klein to start 2025 in the major league bullpen or spend time in Triple-A to keep working on his control, and it's likely to be at least partially determined by his performance at spring training. Regardless, the Mariners are known for their ability to develop young players, and Klein is a perfect redemption story waiting to happen.