Rookie rankings: Tanaka leads the pack 

May, 2, 2014
May 2
11:00
AM ET
With the season's first month in the books, rookies have quickly had significant impact on their teams. The New York Yankees and Kansas City Royals have new top-of-the-rotation rookie starters, the Atlanta Braves and Seattle Mariners are enjoying pleasant surprises in the back of their rotations, while the rookie shortstops of the Boston Red Sox and Arizona Diamondbacks are holding their own.

Once again, I'll be keeping track of this season's rookie class every month, which will be based on performance, scouting reports, advanced metrics, the players' actual development reports from the teams' general managers, managers and front office executives, as well as input from teammates and coaches who will comment on the players' intangibles from inside the clubhouses.

Without further delay, here are my top 10 rookies after the first month of the 2014 season. (Note: When I say a player's stock is "up" or "down," I'm referring to my expectations of him coming into the season.)

1. Masahiro Tanaka | RHP | Stock: Up
Tanaka went 24-0 for Japan's Rakuten Golden Eagles last season and has continued his undefeated streak here in the United States.