I'll try to keep this light, because I could really write like an 8,000 word evisceration. To say that the success rate on top bonus babies is "extremely high" is...not true. Internationally, the hit rate may even be lower. Here's the list of top international bonuses, please show me where this looks like a "sure thing". Sorry if it's hard to read unformatted, that's why I only excerpted the top of the list.
http://www.baseballamerica.com/international/top-40-international-bonuses-time/Player Year Pos Org Age Country Bonus
1. Nomar Mazara 2011 OF Rangers 16 Dominican Republic $4.95 million
2. Jairo Beras 2012 OF Rangers 17 Dominican Republic $4.5 million
3. Michael Ynoa 2008 RHP Athletics 16 Dominican Republic $4.25 million
4. Ronald Guzman 2011 OF Rangers 16 Dominican Republic $3.45 million
5. Miguel Sano 2009 SS Twins 16 Dominican Republic $3.15 million
6. Gilbert Lara 2014 SS Brewers 16 Dominican Republic $3.0975 million
T-7. Dermis Garcia 2014 SS Yankees 16 Dominican Republic $3 million
T-7. Luis Heredia 2010 RHP Pirates 16 Mexico $3 million
T-7. Elier Hernandez 2011 OF Royals 16 Dominican Republic $3 million
T-7. Gary Sanchez 2009 C Yankees 16 Dominican Republic $3 million
11. Adrian Rondon 2014 SS Rays 16 Dominican Republic $2.95 million
T-12. Adonys Cardona 2010 RHP Blue Jays 16 Venezuela $2.8 million
T-12. Eloy Jimenez 2013 OF Cubs 16 Dominican Republic $2.8 million
14. Ariel Ovando 2010 OF Astros 16 Dominican Republic $2.6 million
15. Rafael Rodriguez 2008 OF Giants 16 Dominican Republic $2.55 million