April 6

Joe Williams (1885)
Mickey Cochrane (1903)
Ernie Lombardi (1908)
Phil Regan (1937)
Marty Pattin (1943)
Bert Blyleven (1951)
Kenny Williams (1964)
Bret Boone (1969)
Lou Merloni (1971)

A star in the Negro Leagues, some say that Smokey Joe Williams was a better pitcher than Satchel Paige.

I haven't checked, but my guess is that four Hall-of-Famers born on the same day is the record.

Right-hander Rik Aalbert Blyleven had two stints with the Twins, 1970-1976 and 1985-1988.  He was born in Zeist, Netherlands but attended high school in Garden Grove, California.  Minnesota drafted him in the third round in 1969.  He had an excellent year and two months in the minors, was brought up to the Twins in June of 1970, and never looked back.  He was immediately placed in the starting rotation and went 10-9, 3.18 with five complete games.  He pitched an incredible number of innings for a young pitcher, topping 270 innings every year from age 20-25.  The 3.18 ERA was the highest ERA he had as a Twin the first time around--every other year, he was at 3.00 or lower.  He also had double digit complete games every year in his first time as a Twin, with at least 17 every year but one.  He also struck out over 200 batters every season from 1971-1976.  Remarkably, he only made the all-star team once, in 1973.  He won twenty games that year, finished seventh in Cy Young voting, and got minor consideration for MVP.  On June 1, 1976, the Twins traded Blyleven along with Danny Thompson to Texas for Mike Cubbage, Jim Gideon, Bill Singer, Roy Smalley, and cash.  He continued to be an excellent pitcher with the Rangers, continuing his string of sub-3.00 ERAs and double digit complete games there.  After the 1977 season Blyleven was traded to Pittsburgh as part of a four-team deal.  His ERA started to rise in his Pirates years, but he remained a solid rotation starter and continued to pitch over 200 innings per season.  Blyleven was traded to Cleveland after the 1980 season and responded with some fine years, although he missed much of 1982 due to injury.  1984 was an especially good year, as he went 19-7, 2.87 and finished third for the Cy Young award.  On August 1, 1985, Blyleven was traded back to the Twins for Jay Bell, Curt Wardle, Jim Weaver, and a player to be named later (Richard Yett).  He led the league that year with 24 complete games and 293.1 innings pitched.  He remained in the Twins' starting rotation through 1988, and while his ERA slipped over four for the first time, he continued to be a valuable pitcher, leading the league in innings pitched again in 1986 with 271.2.  After a poor 1988, the Twins traded Blyleven again, this time to California with Kevin Trudeau for Rob Wassenaar, Mike Cook, and Paul Sorrento.  He responded with one of the best years of his career, going 17-5, 2.73 with 241 innings pitched at age 38, finishing fourth in MVP voting.  It was to be the last good year of his career, however; Blyleven struggled in 1990, missed 1991 with injury, struggled again in 1992, and then his career was over.  As a Twin, Bert Blyleven was 149-138, 3.28.  He pitched 2,566.2 innings, had a WHIP of 1.19, made 349 starts, pitched 29 shutouts, and had 141 complete games.  As everyone reading this is aware, Bert Blyleven is currently a television analyst for the Twins on Fox Sports North.  He was inducted into the major league baseball Hall of Fame in 2011.

Second baseman Bret Robert Boone was a member of the Twins for two weeks or so in 2005.  He comes from a baseball family:  his grandfather, Ray, his father, Bob, and his brother, Aaron, were all major league baseball players.  According to wikipedia, he is also a descendant of Daniel Boone.  Bret was born in El Cajon, California, went to high school in Placentia, California, and was drafted by Seattle in the fifth round in 1990.  He started slowly, but came into his own in 1992, when he reached AAA.  He hit .314 in Calgary that year, earning a September call-up.  In 1993, he hit .332 there in a half season.  He came up to the majors to stay in late July.  Boone was traded to Cincinnati after the 1993 season and had a big year in 1994, hitting .320 with 12 homers and getting minor consideration for MVP.  He came crashing back to earth after that, hitting .267, .233, and .223 from 1995-1997.  He bounced back to hit .266 with 24 homers in 1998, making the all-star team and winning a Gold Glove.  Boone then spent a few years on the move, traded to Atlanta after the 1998 season and to San Diego following the 1999 season.  He was a free agent the next year and signed with Seattle for 2001.  He responded with what was easily the best year of his career, hitting .331 with 37 homers and a league-leading 141 RBIs.  He made his second all-star team, won a Silver Slugger award, and finished third in MVP voting.  While he never came close to repeating that season, he continued to hit well.  His 2003 season, in which he hit .294 with 35 homers, got him on another all-star team, another Silver Slugger, and tenth place in MVP balloting.  He also won the Gold Glove from 2002-2004.  He had started to slip in 2004, however, and when he got off to a poor start in 2005 Seattle sent him to Minnesota in July "as part of a conditional deal."  The Twins had a hole at second base that year, but Boone could not fill it:  in 14 games, he hit .170/.241/.170 and was released at the end of the month.  He tried to make a comeback in 2008, signing with Washington, but could not make it back to the big leagues.  Bret Boone was manager of the Victoria Seals in the Golden Baseball League at the start of 2010, but left the position in late May to deal with family matters.  At last report, he was coaching youth baseball in Southern California.  He also speaks to teenagers about his battles with alcoholism.  He is looking to get back into professional baseball in some capacity, but apparently nothing has materialized yet.  On the other hand, he's reportedly dating Rachel Uchitel, so he's got that going for him.