Are Rookies of the Year Yordan Alvarez and Pete Alonso due for sophomore slump?

The Astros’ Yordan Alvarez and Pete Alonso of the Mets ran away with this year’s MLB Rookie of the Year Awards, but they shouldn’t expect the same success in 2020

In section 337 of Houston’s Minute Maid Park, more than 400 feet from home plate and so far away that fans sitting there can safely leave their gloves at home, sits a lone orange seat. This seat, amidst the rest of the green seats that surround the stadium, is a testament to the power of one man.

Yordan Alvarez, the Astros rookie designated hitter, was already well on his way to winning Rookie of the Year honors when he came to bat against the Athletics’ Nick Blackburn on Sept. 9. On the third pitch of the at-bat, Blackburn threw the left-handed hitting Alvarez a 91 mph fastball on the inside corner. Alvarez took a mighty swing and hit the ball high up into the upper deck, a place people who had been watching Astros games for years say they had never seen a ball hit. The orange seat was installed where the ball landed to commemorate the event.

The 22-year-old Alvarez finished the season with 27 home runs in just 87 games played. His 1.067 OPS was the highest of any rookie in history. Only four players ever had an OPS that high before the age of 23: Bryce Harper, Jimmie Foxx, Joe DiMaggio, and Mel Ott. In the modern era only Shoeless Joe Jackson had an OPS within 10 points of Alvarez in his rookie season.

Over a 162-game schedule, he would’ve been projected to hit 50 home runs and 145 RBI. On Monday he became the unanimous winner of the American League Rookie of the Year Award despite not making his Major League debut until June 9.

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But Alvarez still wasn’t the best rookie slugger in baseball this season, because the Mets’ Pete Alonso had a debut season for the record books. The “Polar Bear” set a new rookie record with 53 home runs, becoming the first rookie to lead the NL in home runs since Ralph Kiner and the first to lead the league outright. Alonso too was rewarded, taking home the National League Rookie of the Year Award with all but one first-place vote (Braves’ starting pitcher Mike Soroka received one).

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At this time last year, Alvarez and Alonso were just Minor Leaguers hoping to crack the big league roster in 2019. Now they’re two of the most exciting sluggers in the league, their at-bats must-see TV. Their rookie seasons were so dynamic that it begs the question: can they possibly get any better?

There are signs that both might be in for a regression in 2020.

Big league pitchers discovered something about Alvarez late in the season, and that is he likes to chase pitches out of the zone. Through his first three months of the season he struck out in 28.9 percent of his at-bats. In September, that went up to 33.3 percent. Against the Yankees in the ALCS, Alvarez expanded the strike zone so much he finished the six-game series with just one hit and 12 strikeouts in 22 at-bats.

Leave the ball in the middle of the plate, though, and Alvarez doesn’t miss. He hit above .600 this season on balls up in the zone. The Major League average on similar pitches was .262. He finished the season ranked 14th in baseball in average exit velocity.

For Alonso, his rookie season was a study in consistency. He went into the All-Star break with 30 home runs, one behind Christian Yelich for the league lead. He hit 23 in the second half, behind only the Reds’ Eugenio Suarez. He led the league with 11 home runs in September on his way to breaking Aaron Judge’s rookie home run record. He also shattered the Mets’ single-season record of 41.

Alonso’s power surge was predicated on one thing: get the ball in the air and watch it leave the park. He was one of only four batters who had at least 30 percent of his fly balls result in home runs. His fly ball-to-home-run ratio was nearly double that of MVP candidate Anthony Rendon; another MVP finalist, Cody Bellinger, finished the year at 24.6 percent. Even a slight regression toward the league average will bring down his home run total.

A look at Judge’s career path shows that Alonso can’t count on hitting 50 home runs every year. The Yankees slugger hit 52 home runs in his rookie season in 2017. Over the last two seasons, though, he’s hit 54 combined and hasn’t even reached 30 in either single season. The last six players to lead the league with at least 45 home runs all failed to reach 40 the next year.

There’s one person who expects him to be better next season, and that is Alonso himself. “I hold myself up to high expectations and I want to keep improving, keep climbing the ladder,” he said on Monday after the award announcement. “I just want to keep progressing and keep evolving. Next year I want to be more dynamic.

“People are going to have a book on me after seeing me for a year. But, with that same token, after having experience, understanding how big league pitching is, it’s really nice knowing what to expect going into next season.”

Alvarez helped the Astros to get within one game of the World Series title while Alonso and the Mets won 86 games and finished just three games out of a Wild Card spot. They newly minted Rookies of the Year are key pieces for teams that expect to be contenders next season. But for two young players, that’s a big burden to carry on their sophomore shoulders.