Early years: 2002–2004

Sugiuchi finished with just two wins in his rookie season (2002) in the pros. During the off-season, he made up his mind to abandon the windup and pitch exclusively from the stretch, a decision that led to a breakout sophomore campaign in which he put up 10 wins as a member of the starting rotation alongside rookies Tsuyoshi Wada and Nagisa Arakaki.^[4] Following the Hawks' league title, Sugiuchi started two games in the 2003 Japan Series, winning both starts and being named the Japan Series Most Valuable Player.^[5] He married reporter Erika Ueba during the off-season.

Coming off of a season in which he went 10–8 with a 3.38 ERA and 169 strikeouts, Sugiuchi struggled to live up to expectations to begin the 2004. On June 1, he gave up seven runs in the first two innings in a regular-season start against the Chiba Lotte Marines, slamming both of his fists into the dugout bench in frustration and breaking the fifth metacarpal bone on both hands. He immediately underwent surgery at a hospital, where it was said that he would be sidelined for three months.^[6] The Hawks organization fined Sugiuchi 1 million yen for "conduct unbecoming of a professional baseball pitcher".

2005

Sugiuchi rebounded in the 2005 season,^[7] winning the Pacific League MVP award for the months of April and May^[8] and racking up his first 10 wins at the fastest pace of his career. He finished the season with an 18–4 record, a 2.11 ERA, 218 strikeouts^[9] and 43 walks (a strikeout-to-walk ratio of 5.07), leading the league in wins and ERA and becoming the fourth pitcher in Hawks franchise history to record 200 or more strikeouts in a single season. He also beat out teammate and resident staff ace Kazumi Saito, who had a stellar season himself with a 16–1 record and a 2.92 ERA,^[10] in being voted to the Eiji Sawamura and league Most Valuable Player awards.^[11][12] He also went the entire season without recording a hit-batter, wild pitch, balk, or error.

2006

In 2006, Sugiuchi was named to the Japanese national team to play in the inaugural World Baseball Classic. However, he went 0–1 in two appearances with a 5.40 ERA, being charged with the loss in Japan's second-round match against South Korea. He began strong but struggled as the season went on, putting up just 7 wins (5 losses) with a 3.53 ERA in 132+2⁄3 innings.^[13] He took the mound in the Hawks' first game of the second stage of the Pacific League playoffs, but left the game after giving up two runs in the first three innings and was charged with the loss.

2007

Sugiuchi had another comeback year in 2007, continuing his peculiar tradition of having a good season every other year. He became the Hawks' de facto ace and went 15–6 with a 2.46 ERA, striking out 187 (the second-highest total of his career) in a career-high 197+2⁄3 innings with five complete games and three shutouts. His presence was much-needed after an injury to the team's ace, Kazumi Saito. From April 25 until August 4, Sugiuchi recorded quality starts in 15 of the 16 starts he made, with five complete games and two shutouts. He would not go longer than seven innings for the rest of the season, but did record a Game 2 victory against the Chiba Lotte Marines in the first stage of the Pacific League Climax Series to force a decisive Game 3.

2008

Sugiuchi pitching for Japan in the 2008 Summer Olympics.

Sugiuchi put up another solid season in 2008, going just 10–8 (partly due to the time he missed while pitching for the national team in the 2008 Beijing Olympics^[14]) but striking out a league-leading 213 with a 2.66 ERA while anchoring a rotation that was short Saito and Wada for much of the season.^[15] It marked the first time in his seven-year career that he had recorded double-digit wins or thrown more than 140 innings in consecutive seasons.

On October 7, the Hawks sent Sugiuchi to the mound in their regular-season game against the Tohoku Rakuten Golden Eagles in the hopes of avoiding a last-place finish in the pennant race. He and young Eagles hurler Masahiro Tanaka both threw nine shutout innings, sending the game to extra-innings, but the Eagles won in twelve innings. The Hawks finished the season with the worst record in the league for the first time since 1996.^[16]

2009

Sugiuchi during his tenure with the Fukuoka SoftBank Hawks in 2009

In 2009, Sugiuchi was selected to the national team to play in the second World Baseball Classic,^[17] his fourth time playing in major international competition. He was used solely as a reliever, pitching 6+1⁄3 hitless innings in five appearances. He came on to replace Eagles ace Hisashi Iwakuma in the second match against Cuba in the second round, throwing three shutout innings and being credited with a save.^[18] He was also used as a left-handed specialist in the tournament finals against South Korea.

On April 5, in his first start of the regular season against the Orix Buffaloes, Sugiuchi struck out five over 7+2⁄3 innings to bring his career strikeout total to 1003.^[19] He was the fourth-fastest pitcher in NPB history to amass 1,000 career strikeouts (following Hideo Nomo, Kazuhisa Ishii and Yutaka Enatsu), doing so in 979+1⁄3 innings. He became the 318th pitcher in Japanese professional baseball to amass 1000 career innings in a start against the Eagles on April 26, but gave up four runs (three earned) over seven innings en route to his first loss of the season. He had a strong outing on May 10 against the Saitama Seibu Lions, striking out 12 over eight innings and allowing just one run^[20] and improving his record to 11–0 in the month of May since 2007.

2010

Starting off the 2010 campaign as the Opening Day Starter once again, Sugiuchi recorded a quality start against the Hokkaido Nippon Ham Fighters and got the win over Nippon Ham super-ace, Yu Darvish. Sugiuchi continued his winning ways, but was not as dominant as he had been in the past. Always a bit of a slow starter, he put together a fairly good April, recording a complete-game shutout of the Fighters on the 9th, and he also struck out at least nine batters in all of his starts during the month. However, in his first and last starts of the month, Sugiuchi gave up five runs. Despite having a rough start on May 16, an interleague game against the Tokyo Yakult Swallows, he still remained undefeated in the month, running his record to 13–0 since '07.

Sugiuchi's troubles came to a head with a loss on June 20 against the Saitama Seibu Lions. In that game, he was hit for six runs on seven hits with four walks and four strikeouts in just three innings. It was his shortest start in the regular season since August 20, 2007. Since then, he has recorded quality starts in each of his past four starts, with two complete games against Nippon Ham (a second complete-game shutout) and Seibu. He also started the second game of the 2010 All-Star Series, following the lead of his teammate, Tsuyoshi Wada, who started Game 1.

As 2010 started its Pacific League's end of season race between the Hawks, Lions and Marines, Sugiuchi hit a minor slump just as his team needed him most. Between August 21 and September 18, he had 4 winless games (2 losts, 2 no results). His next game on Sept 25 was at Sapporo against the Fighters, and was the Hawks last second game of the regular season. The Hawks needed a win to maintain their lead in the league against Lions. He faced off against Fighters' ace Darvish and both pitchers went the whole nine innings. In the end, Sugiuchi prevailed as Darvish gave up one run and he gave up none while striking out nine Fighters. A much relieved Sugiuchi then famously broke down in tears at the Hero's interview as he admitted that he finally delivered during the pennant race.