Here are some statistics to help with your decision:
Yu Darvish (25)- Texas Rangers (Japanese/Iranian)
2012 Spring Training:
15 IP, 3.60 ERA, 1.33 WHIP, 21 K
2011 NPB w/ Hokkaido Nippon-Ham Fighters:
232 IP, 1.44 ERA 0.83 WHIP, 276 K
Hisashi Iwakuma (30)- Seattle Mariners (Japanese)
2012 Spring Training:
12 IP, 3.75 ERA, 1.75 WHIP, 9 K
2011 NPB w/ Tohoku Rakuten Golden Eagles:
119 IP, 2.42 ERA, 1.05 WHIP, 90 K
Wei-Yin Chen (26)- Baltimore Orioles (Taiwanese)
2012 Spring Training:
20 IP, 3.60 ERA, 1.15 WHIP, 9 K
2011 NPB w/ Chunichi Dragons:
164.2 IP, 2.68 ERA, 1.03 WHIP, 94 K
Norichika Aoki (30)- Milwaukee Brewers (Japanese)
2012 Spring Training:
59 AB, .305 AVG, .349 OBP, .458 SLG, 4 SO
2011 NPB w/ Tokyo Yakult Swallows:
583 AB, .292 AVG, .358 OBP, .360 SLG, 55 SO
Yoenis Cespedes (26)- Oakland Athletics (Cuban)
2012 Spring Training:
25 AB, .200 AB, .286 OBP, .360 SLG, 7 SO
2010-11 SNC w/ Granma Stallions:
354 AB, .333 AVG, .424 OBP, .667 SLG, 40 SO