KC Royals Roster: Predicting the next three Kansas City 40-man additions

Denny Medley-USA TODAY Sports
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Walter Pennington

We have seen the social media chatter about reliever Walter Pennington. There are several biographical reasons why the 25-year-old should be dismissed. A 2020 undrafted free agent. A Colorado School of Mines alum. A soft-tossing lefty in a high-velocity world. Despite his untypical profile, Pennington is one of Kansas City's and Triple-A's best minor-league relievers.

The lefty received his first major league spring training invite this year, a reward for his impressive 2023 season. He started off in Double-A Northwest Arkansas, making eight appearances and pitching 9⅔ innings. In that span, he made light work of the competition, allowing only four hits and no runs. A Triple-A promotion upped the ante, but Pennington was up for the challenge.

On May 3, they promoted Pennington to Omaha, where he made 41 appearances and went 7-2 with a 3.69 ERA in 61.0 innings pitched. He did not duplicate his Double-A dominance but still showed promise. He finished the season strongly, pitching five innings without allowing a hit or a run in his last two games. 

He picked up this season right where he left off, and then some. He is currently achieving career-high strikeout rates at 38.2% and low walk rates at 9.2%. Omaha has called upon Pennington to be versatile, making both single-inning and multi-inning appearances this season. He even had a four-inning start on May 11, allowing no runs while striking out six. When Duffey's time was up, Pennington was a sensible replacement. Alas, Long got the call, and Pennington remains in Omaha. 

Valid concerns exist regarding how Pennington's pitch arsenal will perform at the next level. He primarily throws a cutter and slider, both of which average well below 90 mph. He mixes in a sinker that doesn't have much movement but has some higher velocity. Pennington doesn't focus on throwing many pitches in the strike zone; instead, he counts on batters swinging at his slider outside the zone.

The results are hard to ignore, despite some red flags. If Kansas City must seek a reliever beyond the 40-man roster, Pennington should still be considered for selection. If Long or even Smith struggle down the stretch, swapping them out for Pennington makes sense.