Yelich's arrival in Milwaukee might be met with more enthusiasm in fantasy than he deserves.
Yes, the move from Miami's Marlins Park (an extreme pitchers' park) to Milwaukee's Miller Park (one of the more hitting-friendly environments in baseball) would be a plus for any hitter. After all, Miller Park's five-year (2013-17) park factor ranked sixth for runs (1.055) and fifth for home runs (1.179), while Marlins Park's park factor ranked last for runs (0.840) and 28th for home runs (0.818) -- though bear in mind that the latter accounts only for the past two seasons after the team moved in the fences. So those numbers are being compared with the other 30 parks' five-year numbers.
While Yelich's arrival in Milwaukee will mean a greater chance at home runs, coupled with a surefire boost in RBIs and runs scored -- he's in much better shape in the latter two, especially now that he's out of Miami -- it's also important to remember that he's one of the most extreme ground-ball hitters in baseball, a trait that makes his numbers less ballpark-dependent than a typical hitter's.
Yelich's 60.1 percent rate since the date of his big league debut in 2013 is third-highest among players with at least 1,000 plate appearances during that time span, though in his defense, he did cut that to a mere 52.2 percent after the 2017 All-Star break.
Should he continue to get greater elevation on the ball, his homer total could soar, perhaps to the point of doubling. That's still a big assumption to make, with the wiser projection boosting him from, say, 20 to 23 homers, while assuming great odds that he will repeat or exceed last season's 100 runs and 81 RBIs.
That's still not yet a top-40 overall player, but I'm moving him up from 53rd to 50th following his trade.
However, it's the key prospect in the Marlins' haul who is most interesting from a fantasy perspective: outfielder Lewis Brinson, who sported ghastly 30.9 percent strikeout and 63.8 percent contact rates in his 21-game cup o' joe with the Brewers last summer. The dramatic contrast between those and his 18.2/79.3 rates for the Brewers' Triple-A affiliate suggests that he might require a lengthy adjustment to the big leagues, something through which the noncontending Marlins can and should have patience.
He'll slide into Yelich's old outfield spot and, barring the team delaying his service-time clock with additional minor league seasoning to begin the year, could get regular (600?) plate appearances. Since Brinson's combination of power and speed provides legitimate 20/20 potential given the at-bats, he's a much more attractive deep-league rotisserie pick now, and in leagues that won't penalize you for bad batting average or strikeouts, he's particularly interesting.
None of the other three prospects the Marlins acquired seems likely to make a major league impact in 2018, but Isan Diaz and Monte Harrison could each be fantasy factors within the next two seasons. Both couple a bit of power with speed, and while neither makes great contact, those are still skills with rotisserie appeal if they develop in the upper levels of the Marlins' system this year.
Back in Milwaukee, Keon Broxton suffers the biggest hit in terms of fantasy value, not that he seemed likely to open the season as a regular for the Brewers in the first place. He's one of the worst in baseball at making contact, and without the at-bats to generate a healthy stolen base total, he's of minimal use even in super-deep leagues. Broxton would be better off being cut or traded to another team with an outfield need, but in all likelihood, he's now off the mixed-league radar for 2018.