Two years ago, Aaron Judge hit 10 April homers on his way to a 52-homer season and securing his place among the elite sluggers in baseball. That same April, Eric Thames hit 11 homers in his first season back in the major leagues, but he was merely an average hitter the rest of the season and ended up without a starting job last season. Both players had to be considered huge surprises, but some surprises have better staying power than others.
Here are this year's big surprises and a look at whether their big starts might have staying power.
Cody Bellinger, Los Angeles Dodgers
Two seasons ago, Bellinger was a superstar in the making, hitting nearly 40 homers in less than a full season's worth of work. As a sophomore, he slumped to 25 homers and looked more like an above-average regular than a star. This season, stardom has struck, with Bellinger pacing the majors with nearly 4 WAR in less than two months. He has increased his walks while cutting his strikeouts nearly in half. Bellinger is on pace for one of the greatest seasons of all time, and while he might not get there, an MVP award is within his grasp.
Jorge Polanco, Minnesota Twins
A couple of years ago, Polanco looked like an average player. Last year, after sitting out the first half of the season with a PED suspension, he looked a little better as a contact hitter without much power to speak of. This season, with 12 doubles, 5 triples and 8 homers, he's hitting like an All-Star for the surprising Twins. Polanco might be a good hitter, but he's not a great one. He can't keep hitting twice as many fly balls as ground balls without a lot more of those flies finding gloves for outs. He can't keep up an isolated slugging percentage of .284 and a BABIP of .354 as pitchers will eventually catch up to him. Polanco is a likely All-Star, but he probably won't keep going like an MVP candidate.
Conventional wisdom held that Gallo needed to strike out less and make contact more in order to maximize his prodigious power. Instead, Gallo has eschewed that strategy by striking out more than a third of the time but walking more and swinging only for the fences. Gallo has cut down on the pitches he's swinging at outside the zone to earn more walks, but he's also not swinging at as many strikes. Gallo's .276 average might not seem that high, but it is likely to come down a bit. Still, a .230 average with his power and a 20 percent walk rate would make him one of the better offensive players in baseball. Gallo's 13 homers put him on pace for close to 50 homers this season, and that's a realistic goal assuming his current 40 percent fly ball rate rises closer to the 50 percent rate from the rest of his career.
Luis Castillo, Cincinnati Reds
After a promising 2017 rookie season, Castillo was a popular breakout pick last year. That didn't materialize as planned, with Castillo's strikeouts and excellent ground ball rate dropping on the way to a pedestrian 4.30 ERA and nearly matching 4.32 FIP. Castillo's signature changeup worked well, but his four-seam fastball got hit hard, and his two-seamer didn't result in ground balls. Castillo has found success this season with the sinking fastball, which is generating a nearly 60 percent ground ball rate, and he's getting batters to chase out of the zone on everything else. His walk rate is up more than 10 percent, but a boost in strikeout rate by one-third more than balances that out. If hitters start taking more pitches, Castillo's 2.64 FIP might end up a little higher -- and he wasn't going to put up a sub-2.00 ERA anyway -- but after last year's step back, Castillo should be a strong starter for the Reds.
Heading into 2019, the 28-year-old Tigers lefty had pitched more than 400 innings as a middling starter. Acquired as a secondary piece in the David Price trade in 2015, Boyd has broken out in a big way with a 2.85 FIP, 3.15 ERA and 30 percent strikeout rate. Boyd's big season can be attributed to a simpler approach. After using five different pitches in previous seasons, Boyd is emphasizing his two best pitches, a four-seam fastball and a slider, using them 87 percent of the time. That recipe has fooled batters for six weeks, but unless he develops a reliable third pitch, hitters might be able to adjust and keep Boyd's breakout from being long-term.
In 2017, Bell hit 26 home runs, but he took a big step back last season with just 12. For a slugging first baseman, Bell simply hit way too many balls on the ground. With a ground ball rate of roughly 50 percent entering the year, Bell couldn't tap into his power, and he pulled the ball only 34 percent of the time, further limiting the damage he could do. This season, Bell has been more aggressive on pitches in the zone, leading to more pulled balls in the air and as many homers as he had all of last season. Bell is striking out more, but that trade-off has been worth it as Bell should eclipse the 30-homer mark for the first time in his career. The switch-hitter might never be great against lefties, but his power against righties should make up for it.
When the Rays acquired Diaz from Cleveland over the winter, the big question was whether Tampa Bay could tap into Diaz's natural power and ability to make hard contact. While Diaz's exit velocities were very good, he hit just 27 homers across five professional seasons. In 299 plate appearances with Cleveland, just one ball left the yard, while more than 50 percent of batted balls were on the ground. This year, Diaz has already hit nine homers, and his .264/.345/.514 batting line is about 40 percent better than league average. It's probably best to temper expectations for the newfound power because Diaz is still hitting about 50 percent of his batted balls into the ground. Those nine homers have come from just 37 fly balls. Unless Diaz can get the ball in the air more consistently, he's not going to hit nine more homers all season.
San Diego Padres rotation
A year ago, Padres starters were the worst in baseball with a 5.09 ERA and 4.71 FIP despite pitching in a park that is at worst neutral for pitchers. Their 822 innings was the lowest total in the National League. Going from worst to middle of the pack might not be award-worthy, but it is certainly a surprise. The team has undergone a remarkable turnaround with an above-average staff that has the Padres in contention in the early going. Rookie Chris Paddack has been amazing, Joey Lucchesi is building on his strong rookie season and Matt Strahm has allowed only eight walks in eight starts. The club hasn't gotten much from Nick Margevicius or Eric Lauer, but so far the positives outweigh the negatives, and a very good defense is certainly helping. If the Padres are going to stay in contention, however, they are going to need help from outside the organization.
Cleveland Indians bullpen
We might not think of Cleveland's bullpen as being a disaster given its pedigree in previous playoff runs, but Cody Allen and Andrew Miller were both disappointments last year. As a club, Cleveland's 4.53 FIP made the bullpen replacement-level, while the relievers' 1.5 homers per nine innings was the worst in the game. This season, Brad Hand is pitching like the relief ace the Indians traded for, while the surprising Nick Wittgren has been a revelation with 18 strikeouts and just one walk. The other Padre in the Hand trade, Adam Cimber, also has pitched well. The season has been somewhat disappointing for Cleveland thus far, but the bullpen has been a bright spot and should help the team stay in contention all season long.
Arizona Diamondbacks offense
When teams lose players of the caliber of Paul Goldschmidt and A.J. Pollock, they shouldn't get better on offense, but that's what has happened in Arizona. The surprising Diamondbacks are still in the race in what was supposed to be a white-flag-waving season after they lost so much over the winter. Christian Walker, the team's 28-year-old first baseman, is hitting better than the player he replaced, Goldschmidt. David Peralta and Eduardo Escobar are having great years, while Jarrod Dyson, Ketel Marte, free-agent signee Adam Jones and Carson Kelly are having above-average seasons with the bat. Only Wilmer Flores and the glove-first Nick Ahmed have gotten significant playing time without helping on offense. While it might be nice to see this crew keep things going, too many hitters are having seasons a bit higher than reasonable expectations, and it is unlikely that they can keep it up all year.