The only appearance Matsui made at the National High School Baseball Championship Tournament was in his second year at PL Academy.

Though Matsui was considered to be the PL Academy's ace starting pitcher, injuries limited him to playing only in the quarter-final game, where he allowed two runs during 22⁄3 innings.

Although Matsui experienced winning the Pacific League Title a total of four times (1994, 1997, 1998, 2002), his team never won the Japanese Series.

According to the Elias Sports Bureau, he is the only Major League player to hit a home run in his first plate appearance of his first three seasons.

The only other player to hit a home run in even his first at-bat of three consecutive seasons was Ken Griffey Jr.

His hits, doubles, home runs, RBI, walks, and total bases ended up being career highs.

By mid-2005, he was no longer an everyday player, sharing time at second base with Miguel Cairo and Marlon Anderson.

Once complete, Matsui was sent down to play with the Rockies' Triple-A affiliate, the Colorado Springs Sky Sox for about two and a half months.

Matsui made his Rockies debut against the Milwaukee Brewers on August 23, 2006, starting at shortstop in place of Clint Barmes.

His stint in New York was punctuated with pronounced booing from Mets fans in response to his failure to validate high expectations gleaned from his (positionally) prodigious Japanese numbers.

[4] Matsui and the Rockies clinched the 2007 National League wild card game by winning a one-game regular season playoff matchup against the San Diego Padres, propelling Colorado into their second playoff appearance in club history.

Matsui became only the third player in MLB history to have his first career grand slam occur in the postseason rather than the regular season.

After the 2010 season, Matsui signed with the Tohoku Rakuten Golden Eagles of Nippon Professional Baseball (NPB).

On November 17, 2017, Matsui signed with the Saitama Seibu Lions of Nippon Professional Baseball (NPB).

[11] On October 13, 2022, Matsui was hired as the manager of the Saitama Seibu Lions, filling the role that was left vacant after Hatsuhiko Tsuji stepped down from the position.