KC Royals 2 biggest losers, 2 winners from May

Winner: Angel Zerpa

This was the month when reliever Angel Zerpa took some burdens off his shoulders. For more than a calendar year, Zerpa's baseball outlook swung between being a starter or coming out of the bullpen. He was the youngest Royals pitcher to start a game since Zack Greinke, but injuries and sub-optimal stuff limited his ceiling. May gave fans the answer they needed. Zerpa is a reliever.

The Venezuela native was, by all accounts, Kansas City's best reliever in May. He appeared in a team-leading 11 games this past month, totaling 9 2/3 innings pitched. He wasn't a dominant strikeout pitcher, but the signs of optimism sustained across May. He only allowed one run this past month while striking out nine and walking three. His 0.82 ERA also led all qualified Royals relievers.

The most significant improvement has to be Zerpa's velocity spike since committing to the bullpen. Let's look at his pitch arsenal's velocity from the past three seasons.

Those velocity spikes have his entire arsenal playing up, especially his sinker. Zerpa still isn't a high-strikeout pitcher, something that Kansas desperately needs right now. But, he produces grounballs at a 58.1% rate, ranking in MLB's 95th percentile.

Royals fans shouldn't start up the All-Star campaign for Zerpa quite yet, but manager Matt Quatraro is trusting the left more as the season progresses. With James McArthur and John Schreiber struggling in Friday's bullpen implosion, Zerpa should continue climbing the relief pecking order.