Alonso has done nothing but hit since cracking the 2019 Mets Opening Day lineup this year. In 29 games, the 24-year-old first baseman posted a .292/.382/.642 with a 170 wRC+ through April 30. He ranks first among qualified National League rookies in slugging, home runs (9), and runs batted in (26).
Overall, Alonso ranks second among National League first baseman in fWAR (1.4), ISO (.336), and wRC+ (166) while coming in third in OPS (1.005) and fourth in batting average (.291). On the Mets, he ranks first in wRC+, ISO, and OPS while coming in second in batting average and third in walk rate. Alonso capped off his phenomenal first month in the major leagues with a walk-off sacrifice fly that helped the Mets defeat the Cincinnati Reds on April 30.
Alonso tied a Mets rookie record originally set by Darryl Strawberry (1983) for nine home runs in one calendar month. He also became just the fourth Met to hit nine home runs before May 1, matching Neil Walker (2016), John Buck (2013), and Carlos Delgado (2006). It originally looked like the Mets might hold Alonso in Triple-A to gain an extra year of control, but his eye-opening spring training performance led to his insertion into the everyday lineup.
On the American League side, Tampa Bay Rays second baseman Brandon Lowe took home Rookie of the Month honors.