The Mariners have benefitted from a strong international scouting department for years. Led by Bob Engle, who is one of the few front office members Jack Zduriencik kept once he was hired, the list is impressive. Chris Snelling, Rafael Soriano, Shin-Soo Choo, Jose Lopez, Cha Seung Baek, Travis Blackley, Felix Hernandez, Jorge Campillo, Asdrubal Cabrera, Yuniesky Betancourt, Ryan Rowland-Smith, Wladimir Balentien, Greg Halman, Cesar Jimenez, Luis Valbuena, Alex Liddi, Michael Pineda, Juan Ramirez, and Carlos Triunfel are all products of Engle and the international scouting department. They are the reason the Mariners farm system was never completely empty under Pat Gillick, despite some bad drafts. Engle's track record alone is enough to get excited about Pimentel.
However, there are other reasons to be excited too. The Mariners have never signed an international prospect to such a big bonus (Kaz, Ichiro, and Kenji are different cases). In fact, part of what makes Engle so impressive is the Mariners rather small budget for international players. They have sunk modest resources into international scouting, but acquired as much talent as anyone. Pimentel's signing bonus indicates that Jack Z is a little more serious about signing international talent. Also, the Mariners have never been a big player in the Dominican Republic, so the Pimentel signing indicates the M's may be extending their international reach just a little bit more.
Bob Engle has been fantastic with modest resources, but I do not think has ever had the money to go after the top-tier international talent. It looks like he does now. It is only a matter of time before the M's farm system is loaded with talent.