With balloting open for the 87th Major League Baseball All-Star Game, fans can start voting for all of their favorite players ahead of the Midsummer Classic in July. If voters were to take a fantasy-centric approach by selecting the biggest fantasy studs so far, the players below would have their names clicked on many ballots.
Welington Castillo, catcher: After opening the season on waivers in many one-catcher leagues, Castillo hit six homers across seven games from April 15-24. Since joining the D-backs during the 2015 season, he has ripped 23 round-trippers across 351 at-bats.
Mark Trumbo, first baseman: Trumbo is off to a great start, and his success cannot solely be ascribed to his relocation to hitter-friendly Camden Yards. In fact, the slugger collected five of his six homers and 17 of his 19 RBIs on the road during April -- with a sizzling five-game stretch from April 11-15 (five homers, 11 RBIs) heavily contributing to his early production.

Jose Altuve, second baseman: Locked in a battle with Bryce Harper for the top spot in '16 fantasy rankings, Altuve has combined surprising power (six homers) with his typically great production in the batting-average (.305) and stolen-base (nine) categories.
Nolan Arenado, third baseman: He, Josh Donaldson and Manny Machado were closely bunched in the first round of most '16 drafts, and they have extended their tightly contested battle for hot-corner supremacy into the regular season. Arenado finished April among the top-5 big leaguers in homers, RBIs and runs, so he gets the nod here.
Trevor Story, shortstop: The most surprising name on this list, Story finished April tied with Arenado for the Major League lead with 10 homers after opening the month on waivers in many leagues. But the rookie may soon relinquish this spot, as he leads the NL in strikeouts (37) and has hit .211 across 57 at-bats since April 14.

Bryce Harper, outfielder: If '16 fantasy leagues redrafted on May 1, Harper would be selected first overall on most occasions. After hitting .330 with 42 homers and a 1.109 OPS last season, the outfielder batted .286 with nine long balls and a 1.121 OPS during April.
Starling Marte, outfielder: Marte was a popular second-round pick in '16 drafts, but he has performed like a first-rounder so far this season. Hitting .323 and on pace to challenge the 20-homer mark and accumulate more than 40 swipes, the 27-year-old is an outstanding five-category contributor.
Mookie Betts, outfielder: Like Marte, Betts has used an impressive combination of power (four homers) and speed (six swipes) to earn a spot on this list. Hitting atop a talented Red Sox lineup, the 23-year-old could be even more productive if he can raise his season .266 average closer to his lifetime .288 mark.

Chris Sale, starter: Though his K/9 rate dropped from 11.8 last season to 7.6 during April, Sale used pinpoint control (1.2 BB/9 rate) to post a stellar 1.66 ERA and 0.68 WHIP during his first five starts this year. If the left-hander can combine his improved walk rate with his career 10.2 K/9 rate the rest of the way, he will be the most valuable fantasy starter of the campaign.
Jake Arrieta, starter: Arrieta punctuated a dominant April (5-0 record, 1.00 ERA, 0.78 WHIP) by throwing a no-hitter on the 21st on the month. Dating back to August 20, 2015, the right-hander has gone 13-0 with a 0.52 ERA and a 0.63 WHIP across 14 starts. And as the ace of a talented Cubs team, Arrieta could reach the 20-win plateau by the end of August.
Jordan Zimmermann, starter: Zimmermann has silenced those who doubted his ability to have success against deep American League lineups by going 5-0 with a 0.55 ERA and a 1.06 WHIP across five April starts. But with a season-to-date 6.3 K/9 rate and a lifetime 7.4 mark, the right-hander will need to continue posting strong ratios in order to qualify as a mixed-league ace for the entirety of '16.
Kenley Jansen, reliever: The first closer off the board in many '16 drafts, Jansen has retained his lofty ranking by posting a 0.84 ERA and a 0.56 WHIP during April. The right-hander also compiled nine saves, and he could lead the National League in that category as the bullpen anchor on a deep Dodgers team.

Andrew Miller, reliever: Miller was arguably the most effective reliever in baseball during April, allowing three hits with zero walks and 15 whiffs across nine scoreless innings. But with Yankees closer Aroldis Chapman expected to return from a suspension during the first half of May, Miller may not record the necessary saves total to stay near the top of the fantasy reliever rankings for the duration of the season.