Ah-seop Son was born on March 18, 1988, in Busan, the second-largest city in South Korea. The left-hander attended Busan High School and was selected by the Lotte Giants in the 2006 KBO draft. He made his professional debut in 2007, at the tender age of 19. That year, Son got little more than a cup of coffee, appearing in four games and receiving only six plate appearances.
Son got his first real taste of professional baseball the following year, when he appeared in 80 games and made 250 plate appearances. The outfielder responded well and hit .303/.387/.404 as a part-time player, but he wasn't able to keep up that level of production. In 2009, he hit just .186/.263/.337, again as a part-time player.
Son got his first real chance to play full-time in 2010. With regular at-bats in the Giants' lineup, Son got into a groove and hit an impressive .306/.377/.438 for the season. Over the following five years, he was a model of consistency, averaging a .333/.408/.477 batting line over that span. During that period, he won four consecutive KBO Gold Glove Awards, awarded to the best overall player at every position on the field.
In 2013, Son was selected to represent South Korea in the 2013 World Baseball Classic. The right fielder batted .250/.400/.250 in total, appearing in two games and getting in a total of four at-bats. He notched one hit and one walk in the tournament, with the hit coming off of Matthew Williams and the walk being issued by Clayton Tanner, both of the Australian World Baseball Classic delegation.
At the end of September, as the Giants were fighting for a playoff spot, it was leaked to the media that Son was interested in playing baseball in the United States and would request to be posted over the offseason. Not long afterward, teammate Jae-Gyun Hwang announced his own intention to be posted, creating an unprecedented situation in which a club had two players seeking to have their rights transferred to an MLB club via the posting system. The official KBO rules and bylaws stated that a team could send only one player to a foreign club per year, but they did not specifically state how many players a team could post over the same offseason. The Giants asked for a clarification in the rules, and the KBO clarified that a team cannot post more than one player per offseason, but it can post a second if the first posting is unsuccessful.
At the end of October, the Giants ended the speculation by announcing that they would post Son—and not Hwang. The team planned on posting Son at the beginning of November, but because of scheduling issues regarding mandatory military service training and playing on the South Korean national team, Son requested that the team post him about a month later instead.
Now that Son has been officially posted, MLB teams will have four business days to submit their bids. Once all bids are in, and the Lotte Giants are informed of the highest bid, they themselves will have four business days to either accept or reject it. If the highest bid is accepted, the winning club will have exclusive rights to negotiate a contract with Son; if the highest bid is rejected, the outfielder will be declared ineligible to play in MLB for the 2016 season and cannot be reposted until November 2016. Should any scenario unfold in which Son is not transferred to an MLB team, the Lotte Giants have stated that they would then immediately post Jae-Gyun Hwang.
First baseman Byung-Ho Park, formerly of the Nexen Heroes, was posted earlier this month, and the Minnesota Twins won the right to negotiate with him for $12.85 million. Son is a year younger and a more versatile player than Park, but does not possess Park's hitting or power skills. It is highly likely that MLB teams bid less for the Giants' outfielder than they did for the Heroes' first baseman.
At the plate, Son utilizes the slide step that is commonly taught to left-handed hitters in Asian countries. He is a gap hitter, but with power on pitches in his two primary hot zones: pitches up and pitches down and in, the lefty wheelhouse. Son does not show any particular weaknesses against left-handed pitching—other than striking out at a higher rate—as he hit .273 against lefties in 129 at-bats in 2015. Generally speaking, however, all of Son's power comes against right-handed pitchers. He hit only nine extra-base hits (eight doubles and one home run) against lefties in 2015, compared to twenty-four (thirteen doubles, one triple, and ten home runs) against righties.
Son has enough speed to takes extra bases and stretch singles into doubles, but he is not a speed demon on the basepaths by any means. Outside of the 2013 season, in which he stole 36 bases in 43 attempts, Son has been little more than an opportunistic base stealer.
Defensively, Son has good range in the outfield—enough to regularly drift into center field but not enough to play center on a regular basis himself. He gets good reads off the bat and is a smart fielder. Because of his strong arm, the left-hander is best suited in right field.
Son's only potential role on the Mets would be as a fourth outfielder or possibly as a platoon mate with Juan Lagares in center. We will soon know whether the Mets put in a bid for his services.