Per ESPN, Roberts has admitted a one-time use of steroids back in 2003.

One of the most circumstantial accusations of the Mitchell report has now proven true. This story seems to be one of a player, struggling in his initial opportunities in the big leagues, searches for the edge to keep himself playing. He uses PEDs, abandons them, and later succeeds without them.

Robert's batting lines:

2002. .227/.308/.297 (128 AB)
      
2003. .270/.337/.367 (460 AB)
      
2004. .273/.344/.376 (641 AB)
      
2005. .314/.387/.515 (561 AB)

The great debate of Japanese stars making the journey from Nippon Professional Baseball to MLB is just how well their skills and abilities will translate in a new league. As with any argument, each side has their successes (Ichiro) and failures (Kazuo Matsui) to point to. For the rest of us, there are statistics. (Warning: Numbers are to follow. Save yourself while you can.)

As with any translation, nothing is exact. And no matter how many players make the move and no matter how many at-bats they accumulate, you'll never be able to forecast what someone else will do from their numbers. Much as I admire Rob Neyer, I don't have his flair for finding the right way to explain how the numbers work, and you're probably tired of "Yet Another Kosuke Fukudome Diary" as it is. So, without further ado, I give you this Excel spreadsheet.

First off, no pitchers were included. This is strictly relating to Fukudome, meaning hitters. Second, I didn't include every Japanese hitter to see time in the Majors, nor did I limit it to only those with significant time in both leagues. I simply chose the names most likely to be recognized with at least one full season of recent playing time (apologies to Tsuyoshi Shinjo.) Statistics were accumulated from ESPN as well as Japanese Baseball and The Baseball Cube.