Jason Heyward is just a year from free agency, but that one year will be a very valuable one, even if he just maintains the status quo. Getting away from the parade of dubious hitting coaches he worked with in Atlanta may help him unlock the still-untapped reserve of superstar potential in his bat.
Heyward consistently rates among the majors' best defensive outfielders in terms of both advanced defensive metrics and traditional evaluations. A decent center fielder in high school, he outgrew the position but maintains the athleticism and strong reads that allowed him to play there as an amateur. He's a smart, disciplined hitter who gets on base at a good clip and doesn't strike out excessively. He did have some trouble maintaining a consistent swing around some shoulder issues; he often cuts off his load, producing too many ground balls with a shorter swing path.
Oscar Taveras' death last month left the Cardinals without a clear right fielder for 2015, and this move locks down the position for just $7.8 million, making the team four or five wins better right away.