The Christian Yelich trade has looked as one-sided as, well, Yelich against big league pitchers. While he won the National League MVP Award and led the Brewers to within a game of the World Series in his first season in Milwaukee and has posted even bigger numbers this season, none of the four youngsters the Marlins received in return have made much of an impact yet in Miami.
The Marlins hope that's on the verge of changing as they will call up Isan Diaz prior to Monday's doubleheader with the Mets, a source told MLB.com's Joe Frisaro. They plan on playing him regularly at second base, giving their previous starter at the keystone (Starlin Castro) some action at the hot corner and using their regular third baseman (Brian Anderson) some in right field.
Diaz came to Miami along with outfielders Lewis Brinson and Monte Harrison and right-hander Jordan Yamamoto in exchange for Yelich in January 2018. Brinson immediately won a starting job with the Marlins, but he batted .199 with a 30 percent strikeout rate in the big leagues until he was demoted in April. He reportedly will get recalled on Monday as well.
After making a splash with a pair of scoreless seven-inning starts in his first two outings in the Majors in mid-June, Yamamoto has been roughed up. Harrison has some of the loudest tools of any prospect anywhere, but he also topped the Minors with 215 strikeouts last year and his 2019 season ended when he fractured his right wrist in June.
Diaz also struggled in his first season in the Marlins system, batting just .232/.340/.399 between Double-A and Triple-A. He has rebounded in 2019, hitting .305/.395/.578 with 26 homers in 102 games at Triple-A New Orleans as a 23-year-old.
Diaz does have a history of producing at the plate, however. A second-round pick by the D-backs out of a Massachusetts high school in 2014, he won MVP honors in the Pioneer League the following summer when he topped the Rookie circuit in slugging (.640), OPS (1.076), doubles (25), extra-base hits (44) and total bases (174). After Arizona sent him to Milwaukee as part of a trade for Jean Segura in January 2016, Diaz led the Class A Midwest League in homers (20), extra-base hits (59) and total bases (238).
With nothing left to prove at the Triple-A level and the Marlins playing for the future, Diaz has an opportunity to get regular at-bats during the final two months of the season. He should provide an offensive upgrade over Castro and similar defense at second base.
Here's a breakdown of Diaz on a tool-by-tool basis:
Hit: With his hand-eye coordination and patience, Diaz is equipped to be at least a solid hitter from the left side of the plate, but he owns just a career .263 average in six pro seasons. He does have an aggressive, pull-happy approach and he works deep counts, which leads to strikeouts. He hasn't exhibited much of a platoon disadvantage in the upper levels of the Minors.
Power: Diaz's best tool is his plus raw power, the product of bat speed and the strength in his compact 5-foot-10, 185 pound frame. He's capable of driving the ball out of the park to all fields, though the majority of his home runs come to his pull side. After having an uppercut in his swing earlier in his career, he has flattened his stroke in recent years and become more of a ground-ball hitter without compromising his home run production. He has 88 homers and a .467 slugging percentage in 583 Minor League games.
Run: Diaz has average speed and good instincts on the bases. He's not much of basestealer, with a 66 percent career success rate and five steals in nine tries this season.
Arm: Like most second basemen, Diaz has ordinary arm strength. That limits his usefulness on the left side of the infield, and though he played a good deal of shortstop early in his career, he hasn't appeared in a Minor League game there since June 2017.
Field: He won't win any Gold Gloves, but Diaz is a reliable defender with average range at second base. The majority of his value will come from his bat, and if he can realize his 25-homer potential that will be more than enough to make him a regular.